We investigate the reliability of standard N-body simulations by modeling of the well-known Hernquist halo with the help of GADGET-2 code (which uses the tree algorithm to calculate the gravitational force) and ph4 code (which uses the direct summation). Comparing the results, we find that the core formation in the halo center (which is conventionally considered as the first sign of numerical effects, to be specific, of the collisional relaxation) has nothing to do with the collisional relaxation, being defined by the properties of the tree algorithm. This result casts doubts on the universally adopted criteria of the simulation reliability in the halo center.

Though we use a halo model, which is theoretically proved to be stationary and stable, a sort of numerical 'violent relaxation' occurs. Its properties suggest that this effect is highly likely responsible for the central cusp formation in cosmological modeling of the large-scale structure, and then the 'core-cusp problem' is no more than a technical problem of N-body simulations.

We propose a novel explanation for the smallness of the observed cosmological constant (CC). Regions of space with a large CC are short lived and are dynamically driven to crunch soon after the end of inflation. Conversely, regions with a small CC are metastable and long lived and are the only ones to survive until late times. While the mechanism assumes many domains with different CC values, it does not result in eternal inflation nor does it require a long period of inflation to populate them. We present a concrete dynamical model, based on a super-cooled first order phase transition in a hidden conformal sector, that may successfully implement such a crunching mechanism. We find that the mechanism can only solve the CC problem up to the weak scale, above which new physics, such as supersymmetry, is needed to solve the CC problem all the way to the UV cutoff scale. The absence of experimental evidence for such new physics already implies a mild little hierarchy problem for the CC. Curiously, in this approach the weak scale arises as the geometric mean of the temperature in our universe today and the Planck scale, hinting at a new "CC miracle", motivating new physics at the weak scale independent of electroweak physics. We further predict the presence of new relativistic degrees of freedom in the CFT that should be visible in the next round of CMB experiments. Our mechanism is therefore predictive and experimentally falsifiable.

We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b₁ and b₂ on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b₁ and b₂ on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b₂(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b₁ and b₂ on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

The connection between galaxy star formation rate (SFR) and dark matter (DM) is of paramount importance for the extraction of cosmological information from next-generation spectroscopic surveys that will target emission line star-forming galaxies. Using publicly available mock galaxy catalogs obtained from various semianalytic models (SAMs), we explore the SFR-DM connection in relation to the speed-from-light method for inferring the growth rate, f, from luminosity/SFR shifts. Emphasis is given to the dependence of the SFR distribution on the environmental density on scales of 10-100 s Mpc. We show that the application of the speed-from-light method to a Euclid-like survey is not biased by environmental effects. In all models, the precision on the measured β = f/b parameter is σ_β ≲ 0.17 at z = 1. This translates into errors of σ_f ∼ 0.22 and ${\sigma }_{(f{\sigma }_{8})}\sim 0.1$ without invoking assumptions on the mass power spectrum. These errors are in the same ballpark as recent analyses of the redshift space distortions in galaxy clustering. In agreement with previous studies, the bias factor, b, is roughly a scale-independent, constant function of the SFR for star-forming galaxies. Its value at z = 1 ranges from 1.2 to 1.5 depending on the SAM recipe. Although in all SAMs, denser environments host galaxies with higher stellar masses, the dependence of the SFR on the environment is more involved. In most models, the SFR probability distribution is skewed to larger values in denser regions. One model exhibits an inverted trend, where high SFR is suppressed in dense environments.

The double copy suggests that the basis of the dynamics of general relativity is Yang-Mills theory. Motivated by the importance of the relativistic two-body problem, we study the classical dynamics of colour-charged particle scattering from the perspective of amplitudes, rather than equations of motion. We explain how to compute the change of colour, and the radiation of colour, during a classical collision. We apply our formalism at next-to-leading order for the colour change and at leading order for colour radiation.

Due to the inverse Primakoff effect, it has been shown that when axions mix with a DC B →-field, the resulting electrical action will produce an AC electromotive force, which oscillates at the Compton frequency of the axion. As in standard electrodynamics, this electromotive force may be modelled as an oscillating effective impressed magnetic current boundary source. We use this result to calculate the sensitivity of new experiments to low-mass axions using the quasi-static technique, defined as when the Compton wavelength of the axion is greater than the dimensions of the experiment. First, we calculate the current induced in a straight conducting wire (electric dipole antenna) in the limit where the DC B →-field can be considered as spatially constant and show that it has a sensitivity proportional to the axion mass. Following this we extend the topology by making use of the full extent of the spatially varying DC B →-field of the electromagnet. This is achieved by transforming the 1D conducting wire to a 2D winding with inductance, to fully link the effective magnetic current boundary source and hence couple to the full axion induced electrical action (or electromotive force). We investigate two different topologies: The first uses a single winding, and couples to the effective short circuit current generated in the winding, which is optimally read out using a sensitive low impedance SQUID amplifier: The second technique uses multiple windings, with every turn effectively increasing the induced voltage, which is proportional to the winding number. The read out of this configuration is optimised by implementing a cryogenic low-noise high input impedance voltage amplifier. The end result is the realisation of new Broadband Electrical Action Sensing Techniques with orders of magnitude improved sensitivity over current low-mass axion experiments, with a sensitivity linearly proportional to the axion-photon coupling and capable of detecting QCD dark matter axions in the mass range of 10^-12 - 10^-8 eV and below.

We report novel cosmological constraints obtained from cosmic voids in the final BOSS DR12 dataset. They arise from the joint analysis of geometric and dynamic distortions of average void shapes (i.e., the stacked void-galaxy cross-correlation function) in redshift space. Our model uses tomographic deprojection to infer real-space void profiles and self-consistently accounts for the Alcock-Paczynski (AP) effect and redshift-space distortions (RSD) without any prior assumptions on cosmology or structure formation. It is derived from first physical principles and provides an extremely good description of the data at linear perturbation order. We validate this model with the help of mock catalogs and apply it to the final BOSS data to constrain the RSD and AP parameters f/b and D_A H/c, where f is the linear growth rate, b the linear galaxy bias, D_A the comoving angular diameter distance, H the Hubble rate, and c the speed of light. In addition, we include two nuisance parameters in our analysis to marginalize over potential systematics. We obtain f/b=0.540±0.091 and D_A H/c=0.588±0.004 from the full void sample at a mean redshift of z=0.51. In a flat ΛCDM cosmology, this implies Ω_m=0.312±0.020 for the present-day matter density parameter. When we use additional information from the survey mocks to calibrate our model, these constraints improve to f/b=0.347±0.023, D_A H/c=0.588±0.003, and Ω_m = 0.310 ± 0.017. However, we emphasize that the calibration depends on the specific model of cosmology and structure formation assumed in the mocks, so the calibrated results should be considered less robust. Nevertheless, our calibration-independent constraints are among the tightest of their kind to date, demonstrating the immense potential of using cosmic voids for cosmology in current and future data.

We apply the classical double copy to the calculation of self-energy of composite systems with multipolar coupling to gravitational field, obtaining next-to-leading order results in the gravitational coupling G_N by generalizing color to kinematics replacement rules known in literature. When applied to the multipolar description of the two-body system, the self-energy diagrams studied in this work correspond to tail processes, whose physical interpretation is of radiation being emitted by the non-relativistic source, scattered by the curvature generated by the binary system and then re-absorbed by the same source. These processes contribute to the conservative two-body dynamics and the present work represents a decisive step towards the systematic use of double copy within the multipolar post-Minkowskian expansion.

Aims: We construct the molecular mass function using the bivariate K-band-mass function (BMF) of the Herschel Reference Survey (HRS), which is a volume-limited sample that has already been widely studied at the entire electromagnetic spectrum.
Methods: The molecular mass function was derived from the K-band and the gas mass cumulative distribution using a copula method, which is described in detail in our previous papers.
Results: The H₂ mass is relatively strongly correlated with the K-band luminosity because of the tight relation between the stellar mass and the molecular gas mass within the sample with a scatter, which is likely due to those galaxies which have lost their molecular content because of environmental effects or because of a larger gas consumption due to past star formation processes. The derived H₂ MF samples the molecular mass range from ∼4 × 10⁶ M_⊙ to ∼10¹⁰ M_⊙, and when compared with theoretical models, it agrees well with the theoretical predictions at the lower end of the mass values; whereas at masses larger than 10¹⁰ M_⊙, the HRS sample may miss galaxies with a large content of molecular hydrogen and the outcomes are not conclusive. The value of the local density of the molecular gas mass inferred from our analysis is ∼1.5 × 10⁷ M_⊙ Mpc^-3, and it is compared with the results at larger redshifts, confirming the lack of strong evolution for the molecular mass density between z = 0 and z = 4.
Conclusions: This is the first molecular mass function that has been derived on a complete sample in the local Universe, which can be used as a reliable calibration at redshift z = 0 for models aiming to predict the evolution of the molecular mass density.

Context. The Asteroid Terrestrial-impact Last Alert System (ATLAS) is an all-sky survey primarily aimed at detecting potentially hazardous near-Earth asteroids. Apart from the astrometry of asteroids, it also produces their photometric measurements that contain information about asteroid rotation and their shape.
Aims: To increase the current number of asteroids with a known shape and spin state, we reconstructed asteroid models from ATLAS photometry that was available for approximately 180 000 asteroids observed between 2015 and 2018.
Methods: We made use of the light-curve inversion method implemented in the Asteroids@home project to process ATLAS photometry for roughly 100 000 asteroids with more than a hundred individual brightness measurements. By scanning the period and pole parameter space, we selected those best-fit models that were, according to our setup, a unique solution for the inverse problem.
Results: We derived ~2750 unique models, 950 of them were already reconstructed from other data and published. The remaining 1800 models are new. About half of them are only partial models, with an unconstrained pole ecliptic longitude. Together with the shape and spin, we also determined for each modeled asteroid its color index from the cyan and orange filter used by the ATLAS survey. We also show the correlations between the color index, albedo, and slope of the phase-angle function.
Conclusions: The current analysis is the first inversion of ATLAS asteroid photometry, and it is the first step in exploiting the huge scientific potential that ATLAS photometry has. ATLAS continues to observe, and in the future, this data, together with other independent photometric measurements, can be inverted to produce more refined asteroid models.

Tables A.1-A.4 are only available in electronic form at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/643/A59

We report significant hard X-ray excesses in the energy range 2-8 keV for two nearby isolated neutron stars: RX J1856.6-3754 and RX J0420.0-5022. These neutron stars have previously been observed in soft X-rays to have nearly thermal spectra at temperatures ∼100 eV, which are thought to arise from the warm neutron star surfaces. We find nontrivial hard X-ray spectra well above the thermal surface predictions with archival data from the XMM-Newton and Chandra X-ray telescopes. We analyze possible systematic effects that could generate such spurious signals, such as nearby X-ray point sources and pileup of soft X-rays, but we find that the hard X-ray excesses are robust to these systematics to the extent that is possible to test. We also investigate possible sources of hard X-ray emission from the neutron stars and find no satisfactory explanation with known mechanisms, suggesting that a novel source of X-ray emission is at play. We do not find high-significance hard X-ray excesses from the other five Magnificent Seven isolated neutron stars.

We present new near-infrared (NIR), JHK_s, time-series observations of RR Lyrae variables in the Messier 3 (NGC 5272) globular cluster using the WIRCam instrument at the 3.6 m Canada-France-Hawaii Telescope. Our observations cover a sky area of ∼21' × 21' around the cluster center and provide an average of 20 epochs of homogeneous JHK_s-band photometry. New homogeneous photometry is used to estimate robust mean magnitudes for 175 fundamental-mode (RRab), 47 overtone-mode (RRc), and 11 mixed-mode (RRd) variables. Our sample of 233 RR Lyrae variables is the largest thus far obtained in a single cluster with time-resolved, multiband NIR photometry. NIR-to-optical amplitude ratios for RR Lyrae in Messier 3 exhibit a systematic increase moving from RRc to short-period (P < 0.6 day) and long-period (P ≳ 0.6 day) RRab variables. We derive JHK_s-band period-luminosity relations for RRab, RRc, and the combined sample of variables. Absolute calibrations based on the theoretically predicted period-luminosity-metallicity relations for RR Lyrae stars yield a distance modulus, $\mu =15.041\pm 0.017\,(\mathrm{statistical})\pm 0.036\,(\mathrm{systematic})$ mag, to Messier 3. When anchored to trigonometric parallaxes for nearby RR Lyrae stars from the Hubble Space Telescope and the Gaia mission, our distance estimates are consistent with those resulting from the theoretical calibrations, albeit with relatively larger systematic uncertainties.

The H0LiCOW collaboration inferred via strong gravitational lensing time delays a Hubble constant value of H₀ = 73.3_-1.8^+1.7 km s^-1 Mpc^-1, describing deflector mass density profiles by either a power-law or stars (constant mass-to-light ratio) plus standard dark matter halos. The mass-sheet transform (MST) that leaves the lensing observables unchanged is considered the dominant source of residual uncertainty in H₀. We quantify any potential effect of the MST with a flexible family of mass models, which directly encodes it, and they are hence maximally degenerate with H₀. Our calculation is based on a new hierarchical Bayesian approach in which the MST is only constrained by stellar kinematics. The approach is validated on mock lenses, which are generated from hydrodynamic simulations. We first applied the inference to the TDCOSMO sample of seven lenses, six of which are from H0LiCOW, and measured H₀ = 74.5_-6.1^+5.6 km s^-1 Mpc^-1. Secondly, in order to further constrain the deflector mass density profiles, we added imaging and spectroscopy for a set of 33 strong gravitational lenses from the Sloan Lens ACS (SLACS) sample. For nine of the 33 SLAC lenses, we used resolved kinematics to constrain the stellar anisotropy. From the joint hierarchical analysis of the TDCOSMO+SLACS sample, we measured H₀ = 67.4_-3.2^+4.1 km s^-1 Mpc^-1. This measurement assumes that the TDCOSMO and SLACS galaxies are drawn from the same parent population. The blind H0LiCOW, TDCOSMO-only and TDCOSMO+SLACS analyses are in mutual statistical agreement. The TDCOSMO+SLACS analysis prefers marginally shallower mass profiles than H0LiCOW or TDCOSMO-only. Without relying on the form of the mass density profile used by H0LiCOW, we achieve a ∼5% measurement of H₀. While our new hierarchical analysis does not statistically invalidate the mass profile assumptions by H0LiCOW - and thus the H₀ measurement relying on them - it demonstrates the importance of understanding the mass density profile of elliptical galaxies. The uncertainties on H₀ derived in this paper can be reduced by physical or observational priors on the form of the mass profile, or by additional data.

ARRAY(0x2329100)

We develop an Effective Field Theory (EFT) formalism to solve for the conservative dynamics of binary systems in gravity via Post-Minkowskian (PM) scattering data. Our framework combines a systematic EFT approach to compute the deflection angle in the PM expansion, together with the `Boundary-to-Bound' (B2B) dictionary introduced in [1, 2]. Due to the nature of scattering processes, a remarkable reduction of complexity occurs both in the number of Feynman diagrams and type of integrals, compared to a direct EFT computation of the potential in a PM scheme. We provide two illustrative examples. Firstly, we compute all the conservative gravitational observables for bound orbits to 2PM, which follow from only one topology beyond leading order. The results agree with those in [1, 2], obtained through the `impetus formula' applied to the classical limit of the one loop amplitude in Cheung et al. [3]. For the sake of comparison we reconstruct the conservative Hamiltonian to 2PM order, which is equivalent to the one derived in [3] from a matching calculation. Secondly, we compute the scattering angle due to tidal effects from the electric- and magnetic-type Love numbers at leading PM order. Using the B2B dictionary we then obtain the tidal contribution to the periastron advance. We also construct a Hamiltonian including tidal effects at leading PM order. Although relying on (relativistic) Feynman diagrams, the EFT formalism developed here does not involve taking the classical limit of a quantum amplitude, neither integrals with internal massive fields, nor additional matching calculations, nor spurious (`super-classical') infrared singularities. By construction, the EFT approach can be automatized to all PM orders.

In previous work, we developed a deep neural network classifier that only relies on phase-space information to obtain a catalog of accreted stars based on the second data release of Gaia (DR2). In this paper, we apply two clustering algorithms to identify velocity substructure within this catalog. We focus on the subset of stars with line-of-sight velocity measurements that fall in the range of Galactocentric radii $r\in [6.5,9.5]\,{\rm{kpc}}$ and vertical distances $| z| \lt 3\,{\rm{kpc}}$ . Known structures such as Gaia Enceladus and the Helmi stream are identified. The largest previously unknown structure, Nyx, is a vast stream consisting of at least 200 stars in the region of interest. This study displays the power of the machine-learning approach by not only successfully identifying known features but also discovering new kinematic structures that may shed light on the merger history of the Milky Way.

We present FEYNCALC 9.3, a new stable version of a powerful and versatile MATHEMATICA package for symbolic quantum field theory (QFT) calculations. Some interesting new features such as highly improved interoperability with other packages, automatic extraction of the ultraviolet divergent parts of 1-loop integrals, support for amplitudes with Majorana fermions and γ-matrices with explicit Dirac indices are explained in detail. Furthermore, we discuss some common problems and misunderstandings that may arise in the daily usage of the package, providing explanations and workarounds.

We investigate how loop-level propagators arise from tree level via a forward-limit procedure in two modern approaches to scattering amplitudes, namely the BCFW recursion relations and the scattering equations formalism. In the first part of the paper, we revisit the BCFW construction of one-loop integrands in momentum space, using a convenient parametrisation of the D-dimensional loop momentum. We work out explicit examples with and without supersymmetry, and discuss the non-planar case in both gauge theory and gravity. In the second part of the paper, we study an alternative approach to one-loop integrands, where these are written as worldsheet formulas based on new one-loop scattering equations. These equations, which are inspired by BCFW, lead to standard Feynman-type propagators, instead of the `linear'-type loop-level propagators that first arose from the formalism of ambitwistor strings. We exploit the analogies between the two approaches, and present a proof of an all-multiplicity worldsheet formula using the BCFW recursion.

Context. The formation of gas giant planets by the accretion of 100 km diameter planetesimals is often thought to be inefficient. A diameter of this size is typical for planetesimals and results from self-gravity. Many models therefore use small kilometer-sized planetesimals, or invoke the accretion of pebbles. Furthermore, models based on planetesimal accretion often use the ad hoc assumption of planetesimals that are distributed radially in a minimum-mass solar-nebula way.
Aims: We use a dynamical model for planetesimal formation to investigate the effect of various initial radial density distributions on the resulting planet population. In doing so, we highlight the directive role of the early stages of dust evolution into pebbles and planetesimals in the circumstellar disk on the subsequent planet formation.
Methods: We implemented a two-population model for solid evolution and a pebble flux-regulated model for planetesimal formation in our global model for planet population synthesis. This framework was used to study the global effect of planetesimal formation on planet formation. As reference, we compared our dynamically formed planetesimal surface densities with ad hoc set distributions of different radial density slopes of planetesimals.
Results: Even though required, it is not the total planetesimal disk mass alone, but the planetesimal surface density slope and subsequently the formation mechanism of planetesimals that enables planetary growth through planetesimal accretion. Highly condensed regions of only 100 km sized planetesimals in the inner regions of circumstellar disks can lead to gas giant growth.
Conclusions: Pebble flux-regulated planetesimal formation strongly boosts planet formation even when the planetesimals to be accreted are 100 km in size because it is a highly effective mechanism for creating a steep planetesimal density profile. We find that this leads to the formation of giant planets inside 1 au already by pure 100 km planetesimal accretion. Eventually, adding pebble accretion regulated by pebble flux and planetesimal-based embryo formation as well will further complement this picture.

The gravitational field of a massive object (for instance, of a galaxy group or cluster) disturbs the Hubble stream, decreasing its speed. Dependence v (r₀) of the radial velocity of the stream on the present-day radius r₀ can be directly observed and may provide valuable information about the cluster properties. We offer an exact analytical relationship v (r₀) for a spherically symmetric system.

Asymptotically flat spacetimes admit both supertranslations and Lorentz transformations as asymptotic symmetries. Furthermore, they admit super-Lorentz transformations, namely superrotations and superboosts, as outer symmetries associated with super-angular momentum and super-center-of-mass charges. In this paper, we present comprehensively the flux-balance laws for all such BMS charges. We distinguish the Poincaré flux-balance laws from the proper BMS flux-balance laws associated with the three relevant memory effects defined from the shear, namely, the displacement, spin and center-of-mass memory effects. We scrutinize the prescriptions used to define the angular momentum and center-of-mass. In addition, we provide the exact form of all Poincaré and proper BMS flux-balance laws in terms of radiative symmetric tracefree multipoles. Fluxes of energy, angular momentum and octupole super-angular momentum arise at 2.5PN, fluxes of quadrupole supermomentum arise at 3PN and fluxes of momentum, center-of-mass and octupole super-center-of-mass arise at 3.5PN. We also show that the BMS flux-balance laws lead to integro-differential consistency constraints on the radiation-reaction forces acting on the sources. Finally, we derive the exact form of all BMS charges for both an initial Kerr binary and a final Kerr black hole in an arbitrary Lorentz and supertranslation frame, which allows to derive exact constraints on gravitational waveforms produced by binary black hole mergers from each BMS flux-balance law.

The hadronic weak decays of Λ_c are studied in the framework of a constituent quark model. With the combined analysis of the Cabbibo-favored processes, Λ_c→Λ π⁺, Σ⁰π⁺, and Σ⁺π⁰, we confirm that the nonfactorizable transition mechanisms play a crucial role in the understanding of their compatible branching ratios. We emphasize that the SU(3) flavor symmetry breaking effects, which is generally at the order of 1-2%, can be amplified by the destructive interferences among the pole terms in the diagrams with internal conversion. Some contributions are sensitive to the spatial distribution of the scalar-isoscalar light-quark sector in the Λ_c, and its overlap with the light quarks in the final state hyperon. Namely, a compact diquark configuration is disfavored.

To understand the nature of the accelerated expansion of the Universe, we need to combine constraints on the expansion rate and growth of structure. The growth rate is usually extracted from 3D galaxy maps by exploiting the effects of peculiar motions on galaxy clustering. However, theoretical models of the probability distribution function (PDF) of galaxy pairwise peculiar velocities are not accurate enough on small scales to reduce the error on theoretical predictions to the level required to match the precision expected for measurements from future surveys. Here, we improve the modelling of the pairwise velocity distribution by using the Skew-T PDF, which has non-zero skewness and kurtosis. Our model accurately reproduces the redshift space multipoles (monopole, quadrupole, and hexadecapole) predicted by N-body simulations, above scales of about $10\, h^{-1}{\rm Mpc}$ . We illustrate how a Taylor expansion of the streaming model can reveal the contributions of the different moments to the clustering multipoles, which are independent of the shape of the velocity PDF. The Taylor expansion explains why the Gaussian streaming model works well in predicting the first two redshift space multipoles, although the velocity PDF is non-Gaussian even on large scales. Indeed, any PDF with the correct first two moments would produce precise results for the monopole down to scales of about $10\, h^{-1}{\rm Mpc}$ , and for the quadrupole down to about $30\, h^{-1}{\rm Mpc}$ . An accurate model for the hexadecapole needs to include higher order moments.

On-shell amplitude methods have proven to be extremely efficient for calculating anomalous dimensions. We further elaborate on these methods to show that, by the use of an angular momentum decomposition, the one-loop anomalous dimensions can be reduced to essentially a sum of products of partial waves. We apply this to the SM EFT, and show how certain classes of anomalous dimensions have their origin in the same partial-wave coefficients. We also use our result to obtain a generic formula for the one-loop anomalous dimensions of nonlinear sigma models at any order in the energy expansion, and apply our method to gravity, where it proves to be very advantageous even in the presence of IR divergencies.

If dark matter has strong self-interactions, future astrophysical and cosmological observations, together with a clearer understanding of baryonic feedback effects, might be used to extract the velocity dependence of the dark matter scattering rate. To interpret such data, we should understand what predictions for this quantity are made by various models of the underlying particle nature of dark matter. In this paper, we systematically compute this function for fermionic dark matter with light bosonic mediators of vector, scalar, axial vector, and pseudoscalar type. We do this by matching to the nonrelativistic effective theory of self-interacting dark matter and then computing the spin-averaged viscosity cross section nonperturbatively by solving the Schrödinger equation, thus accounting for any possible Sommerfeld enhancement of the low-velocity cross section. In the pseudoscalar case, this requires a coupled-channel analysis of different angular momentum modes. We find, contrary to some earlier analyses, that nonrelativistic effects only provide a significant enhancement for the cases of light scalar and vector mediators. Scattering from light pseudoscalar and axial vector mediators is well described by tree-level quantum field theory.

Axion dark matter (DM) may convert to radio-frequency electromagnetic radiation in the strong magnetic fields around neutron stars. The radio signature of such a process would be an ultranarrow spectral peak at a frequency determined by the mass of the axion particle. We analyze data we collected from the Robert C. Byrd Green Bank Telescope in the L band and the Effelsberg 100-m Telescope in the L band and S band from a number of sources expected to produce bright signals of axion-photon conversion, including the Galactic center of the Milky Way and the nearby isolated neutron stars RX J0720.4-3125 and RX J0806.4-4123. We find no evidence for axion DM and are able to set constraints on the existence of axion DM in the highly motivated mass range between ∼5 and 11 μ eV with the strongest constraints to date on axions in the ∼10 - 11 μ eV range.

On-shell amplitude methods allow to derive one-loop renormalization effects from just tree-level amplitudes, with no need of loop calculations. We derive a simple formula to obtain the anomalous dimensions of higher-dimensional operators from a product of tree-level amplitudes. We show how this works for dimension-6 operators of the Standard Model, providing explicit examples of the simplicity, elegance and efficiency of the method. Many anomalous dimensions can be calculated from the same Standard Model tree-level amplitude, displaying the attractive recycling aspect of the on-shell method. With this method, it is possible to relate anomalous dimensions that in the Feynman approach arise from very different diagrams, and obtain non-trivial checks of their relative coefficients. We compare our results to those in the literature, where ordinary methods have been applied.

Axion-photon interactions can lead to an enhancement of the electromagnetic field by parametric resonance in the presence of a cold axion background, for modes with a frequency close to half the axion mass. In this paper, we study the role of the axion momentum dispersion as well as the effects of a background gravitational potential, which can detune the resonance due to gravitational redshift. We show, by analytical as well as numerical calculations, that the resonance leads to an exponential growth of the photon field only if (a) the axion momentum spread is smaller than the inverse resonance length, and (b) the gravitational detuning distance is longer than the resonance length. For realistic parameter values, both effects strongly suppress the resonance and prevent the exponential growth of the photon field. In particular, the redshift due to the gravitational potential of our galaxy prevents the resonance from developing for photons in the observable frequency range, even assuming that all the dark matter consists of a perfectly cold axion condensate. For axion clumps with masses below ~ 10^-13 M_solar, the momentum spread condition is more restrictive, whereas, for more massive clumps, the redshift condition dominates.

Indirect detection of dark matter via its annihilation products is a key technique in the search for dark matter in the form of weakly interacting massive particles (WIMPs). Strong constraints exist on the annihilation of WIMPs to highly visible Standard Model final states such as photons or charged particles. In the case of s-wave annihilation, this typically eliminates thermal relic cross sections for dark matter of mass below Script O(10) GeV . However, such limits typically neglect the possibility that dark matter may annihilate to assumed invisible or hard-to-detect final states, such as neutrinos. This is a difficult paradigm to probe due to the weak neutrino interaction cross section. Considering dark matter annihilation in the Galactic halo, we study the prospects for indirect detection using the Hyper-Kamiokande (HyperK) neutrino experiment, for dark matter of mass below 1 GeV . We undertake a dedicated simulation of the HyperK detector, which we benchmark against results from the similar Super-Kamiokande experiment and HyperK physics projections. We provide projections for the annihilation cross-sections that can be probed by HyperK for annihilation to muon or neutrino final states, and discuss uncertainties associated with the dark matter halo profile. For neutrino final states, we find that HyperK is sensitive to thermal annihilation cross-sections for dark matter with mass around 20 MeV, assuming an NFW halo profile. We also discuss the effects of neutron tagging, and prospects for improving the reach at low mass.

We examine the robustness of collider phenomenology predictions for a dark sector scenario with QCD-like properties. Pair production of dark quarks at the LHC can result in a wide variety of signatures, depending on the details of the new physics model. A particularly challenging signal results when prompt production induces a parton shower that yields a high multiplicity of collimated dark hadrons with subsequent decays to Standard Model hadrons. The final states contain jets whose substructure encodes their non-QCD origin. This is a relatively subtle signature of strongly coupled beyond the Standard Model dynamics, and thus it is crucial that analyses incorporate systematic errors to account for the approximations that are being made when modeling the signal. We estimate theoretical uncertainties for a canonical substructure observable designed to be sensitive to the gauge structure of the underlying object, the two-point energy correlator e₂^{(β )}, by computing envelopes between resummed analytic distributions and numerical results from Pythia. We explore the separability against the QCD background as the confinement scale, number of colors, number of flavors, and dark quark masses are varied. Additionally, we investigate the uncertainties inherent to modeling dark sector hadronization. Simple estimates are provided that quantify one's ability to distinguish these dark sector jets from the overwhelming QCD background. Such a search would benefit from theory advances to improve the predictions, and the increase in statistics using the data to be collected at the high luminosity LHC.

A galaxy's morphological features encode details about its gas content, star formation history, and feedback processes, which play important roles in regulating its growth and evolution. We use deep convolutional neural networks (CNNs) to learn a galaxy's optical morphological information in order to estimate its neutral atomic hydrogen (H I) content directly from Sloan Digital Sky Survey (SDSS) gri image cutouts. We are able to accurately predict a galaxy's logarithmic H I mass fraction, ${ \mathcal M }\equiv \mathrm{log}({M}_{{\rm{H}}{\rm\small{I}}}/{M}_{\star })$ , by training a CNN on galaxies in the Arecibo Legacy Fast ALFA Survey (ALFALFA) 40% sample. Using pattern recognition, we remove galaxies with unreliable ${ \mathcal M }$ estimates. We test CNN predictions on the ALFALFA 100%, extended Galaxy Evolution Explorer Arecibo SDSS Survey, and Nançay Interstellar Baryons Legacy Extragalactic Survey catalogs, and find that the CNN consistently outperforms previous estimators. The H I-morphology connection learned by the CNN appears to be constant in low- to intermediate-density galaxy environments, but it breaks down in the highest-density environments. We also use a visualization algorithm, Gradient-weighted Class Activation Maps, to determine which morphological features are associated with low or high gas content. These results demonstrate that CNNs are powerful tools for understanding the connections between optical morphology and other properties, as well as for probing other variables, in a quantitative and interpretable manner.

The hydrogen-poor supernova (SN) PTF11rka (z = 0.0744), reported by the Palomar Transient Factory, was observed with various telescopes starting a few days after the estimated explosion time of 2011 December 5 UT and up to 432 rest-frame days thereafter. The rising part of the light curve was monitored only in the R_PTF filter band, and maximum in this band was reached ~30 rest-frame days after the estimated explosion time. The light curve and spectra of PTF11rka are consistent with the core-collapse explosion of a ~10 M_⊙ carbon-oxygen core evolved from a progenitor of main-sequence mass 25-40 M_⊙, that liberated a kinetic energy E_k≈4 × 10⁵¹ erg, expelled ~8 M_⊙ of ejecta, and synthesized ~0.5 M_⊙ of ⁵⁶Ni. The photospheric spectra of PTF11rka are characterized by narrow absorption lines that point to suppression of the highest ejecta velocities (≳ 15 000 km s^-1). This would be expected if the ejecta impacted a dense, clumpy circumstellar medium. This in turn caused them to lose a fraction of their energy (~5 × 10⁵⁰ erg), less than 2 per cent of which was converted into radiation that sustained the light curve before maximum brightness. This is reminiscent of the superluminous SN 2007bi, the light-curve shape and spectra of which are very similar to those of PTF11rka, although the latter is a factor of 10 less luminous and evolves faster in time. PTF11rka is in fact more similar to gamma-ray burst SNe in luminosity, although it has a lower energy and a lower E_k/M_ej ratio.

The SPHERE-2 balloon-borne detector designed for extensive air shower (EAS) observations using EAS optical Vavilov-Cherenkov radiation ("Cherenkov light"), reflected from the snow-covered surface of Lake Baikal is described. We briefly discuss the concept behind the reflected Cherenkov light method, characterize the conditions at the experimental site and overview the construction of the tethered balloon used to lift the SPHERE-2 telescope above the surface. This paper is mainly dedicated to a detailed technical description of the detector, including its optical system, sensitive elements, electronics, and data acquisition system (DAQ). The results of some laboratory and field tests of the optical system are presented.

The trans-Neptunian object 2014 MU69, named Arrokoth, is the most recent evidence that planetesimals did not form by successive collisions of smaller objects, but by the direct gravitational collapse of a pebble cloud. But what process sets the physical scales on which this collapse may occur? Star formation has the Jeans mass, that is, when gravity is stronger than thermal pressure, helping us to understand the mass of our Sun. But what controls mass and size in the case of planetesimal formation? Both asteroids and Kuiper Belt objects show a kink in their size distribution at 100 km. Here we derive a gravitational collapse criterion for a pebble cloud to fragment to planetesimals, showing that a critical mass is needed for the clump to overcome turbulent diffusion. We successfully tested the validity of this criterion in direct numerical simulations of planetesimal formation triggered by the streaming instability. Our result can therefore explain the sizes for planetesimals found forming in streaming instability simulations in the literature, while not addressing the detailed size distribution. We find that the observed characteristic diameter of ∼100 km corresponds to the critical mass of a pebble cloud set by the strength of turbulent diffusion stemming from streaming instability for a wide region of a solar nebula model from 2 to 60 au, with a tendency to allow for smaller objects at distances beyond and at late times, when the nebula gas gets depleted.

We analyze constraints on the anomalous Wtb couplings from B-physics experiments, performing a correlated analysis and allowing all anomalous couplings to differ simultaneously from their Standard Model (SM) values. The B-physics observables allow one to probe three linear combinations out of the four anomalous couplings, which parameterize the Wtb vertex under the assumption that the SM symmetries remain the symmetries of the effective theory. The constraints in this work are obtained by taking into account the following B-physics observables: the B¯0-B0 oscillations, the leptonic B→μ+μ- decays, the inclusive radiative B→Xsγ decays, and the differential branching fractions in the semileptonic inclusive B→Xsμ+μ- and exclusive B→(K,K*)μ+μ- decays at small q2, with q the momentum of the μ+μ- pair. We find that the SM values of the anomalous couplings belong to the 95% CL allowed region obtained this way, but lie beyond the 68% allowed region. We also report that the distributions of the anomalous couplings obtained within our scenario differ from the results of the 1D scenario, when only one of the couplings is allowed to deviate from its SM value.

This work investigates a simple, representative extension of the Standard Model with a real scalar singlet and spontaneous Z₂ breaking, which allows for a strongly first-order phase transition, as required by electroweak baryogenesis. We perform analytical and numerical calculations that systematically include one-loop thermal effects, Coleman-Weinberg corrections, and daisy resummation, as well as evaluation of bubble nucleation. We study the rich thermal history and identify the conditions for a strongly first-order electroweak phase transition with nearly degenerate extrema at zero temperature. This requires a light scalar with mass below 50 GeV. Exotic Higgs decays, as well as Higgs coupling precision measurements at the LHC and future collider facilities, will test this model. Additional information may be obtained from future collider constraints on the Higgs self-coupling. Gravitational-wave signals are typically too low to be probed by future gravitational wave experiments.

We present the generalization of recently introduced observables for the studies of correlated fluctuations of different anisotropic flow amplitudes, dubbed symmetric cumulants. We introduce a new set of higher order observables and outline a unique way to extract the genuine multiharmonic correlations from multiparticle azimuthal correlators. We argue that correlations among flow amplitudes can be studied reliably with the general mathematical formalism of cumulants only if that formalism is applied directly on the flow amplitudes. We have tested all the desired properties of new observables with the carefully designed toy Monte Carlo studies. By using the realistic iEBE-VISHNU model, we have demonstrated that their measurements are feasible and we have provided the predictions for the centrality dependence in Pb-Pb collisions at Large Hadron Collider (LHC) energies. A separate study was performed for their values in the coordinate space. The new observables contain information which is inaccessible to individual flow amplitudes and correlated fluctuations of only two flow amplitudes, and therefore they provide further and independent constraints for the initial conditions and the properties of quark-gluon plasma in high-energy nuclear collisions.

Context. When we wish to understand planetesimal formation, the only data set we have is our own Solar System. The Solar System is particularly interesting because so far, it is the only planetary system we know of that developed life. Understanding the conditions under which the solar nebula evolved is crucial in order to understand the different processes in the disk and the subsequent dynamical interaction between (proto-)planets after the gas disk has dissolved.
Aims: Protoplanetary disks provide a plethora of different parameters to explore. The question is whether this parameter space can be constrained, allowing simulations to reproduce the Solar System.
Methods: Models and observations of planet formation provide constraints on the initial planetesimal mass in certain regions of the solar nebula. By making use of pebble flux-regulated planetesimal formation, we performed a parameter study with nine different disk parameters such as the initial disk mass, the initial disk size, the initial dust-to-gas ratio, the turbulence level, and others.
Results: We find that the distribution of mass in planetesimals in the disk depends on the timescales of planetesimal formation and pebble drift. Multiple disk parameters can affect the pebble properties and thus planetesimal formation. However, it is still possible to draw some conclusions on potential parameter ranges.
Conclusions: Pebble flux-regulated planetesimal formation appears to be very robust, allowing simulations with a wide range of parameters to meet the initial planetesimal constraints for the solar nebula. This means that it does not require much fine-tuning.

Scalar hair of black holes in theories with a shift symmetry are constrained by the no-hair theorem of Hui and Nicolis, assuming spherical symmetry, time-independence of the scalar field and asymptotic flatness. The most studied counterexample is a linear coupling of the scalar with the Gauss-Bonnet invariant. However, in this case the norm of the shift-symmetry current J² diverges at the horizon casting doubts on whether the solution is physically sound. We show that this is not an issue since J² is not a scalar quantity, since J^μ is not a diffinvariant current in the presence of Gauss-Bonnet. The same theory can be written in Horndeski form with a non-analytic function G₅∼ log X . In this case the shift-symmetry current is diff-invariant, but contains powers of X in the denominator, so that its divergence at the horizon is again immaterial. We confirm that other hairy solutions in the presence of non-analytic Horndeski functions are pathological, featuring divergences of physical quantities as soon as one departs from time-independence and spherical symmetry. We generalise the no-hair theorem to Beyond Horndeski and DHOST theories, showing that the coupling with Gauss-Bonnet is necessary to have hair.

We discuss the prospects of high precision pointing of our transmitter to habitable planets around Galactic main sequence stars. For an efficient signal delivery, the future sky positions of the host stars should be appropriately extrapolated with accuracy better than the beam opening angle $\Theta$ of the transmitter. Using the latest data release (DR2) of Gaia, we estimate the accuracy of the extrapolations individually for $4.7\times 10^7$ FGK stars, and find that the total number of targets could be $\sim 10^7$ for the accuracy goal better than 1". Considering the pairwise nature of communication, our study would be instructive also for SETI (Search for Extraterrestrial Intelligence), not only for sending signals outward.

The Born cross section and dressed cross section of $ e^+e^-\to b\bar{b} $?--> and the total hadronic cross section in $ e^+e^- $?--> annihilation in the bottomonium energy region are calculated based on the $ R_b $?--> values measured by the BaBar and Belle experiments. The data are used to calculate the vacuum polarization factors in the bottomonium energy region, and to determine the resonant parameters of the vector bottomonium(-like) states $ Y(10750) $?--> , $ \Upsilon(5S) $?--> , and $ \Upsilon(6S) $?--> . * Supported in part by National Natural Science Foundation of China (NSFC) (11521505, 11475187, 11375206); Key Research Program of Frontier Sciences, CAS, (QYZDJ-SSW-SLH011); the CAS Center for Excellence in Particle Physics (CCEPP); and the Munich Institute for Astro- and Particle Physics (MIAPP) which is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy-EXC-2094-390783311

We present an effective field theory for doubly heavy baryons that goes beyond the compact heavy diquark approximation. The heavy quark distance r is only restricted to m_Q≫1 /r ≫E_bin , where m_Q is the mass of the heavy quark and E_bin the typical binding energy. This means that the size of the heavy diquark can be as large as the typical size of a light hadron. We start from nonrelativistic QCD, and build the effective field theory at next-to-leading order in the 1 /m_Q expansion. At leading order the effective field theory reduces to the Born-Oppenheimer approximation. The Born-Oppenheimer potentials are obtained from available lattice QCD data. The spectrum for double charm baryons below threshold is compatible with most of the lattice QCD results. We present for the first time the full spin averaged double bottom baryon spectrum below threshold based on QCD. We also present model-independent formulas for the spin splittings.

Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized n ⃗p scattering performed in the energy region of the d^*(2380 ) dibaryon resonance covering the range of beam energies T_n=0.98 -1.29 GeV (√{s }=2.32 -2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process d p →n p +p_spectator . In this way the n p differential cross section σ (Θ ) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power A_y(Θ ) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled ^D3₃-^G3₃ waves.

We study the Voronoi volume function (VVF) - the distribution of cell volumes (or inverse local number density) in the Voronoi tessellation of any set of cosmological tracers (galaxies/haloes). We show that the shape of the VVF of biased tracers responds sensitively to physical properties such as halo mass, large-scale environment, substructure, and redshift-space effects, making this a hitherto unexplored probe of both primordial cosmology and galaxy evolution. Using convenient summary statistics - the width, median, and a low percentile of the VVF as functions of average tracer number density - we explore these effects for tracer populations in a suite of N-body simulations of a range of dark matter models. Our summary statistics sensitively probe primordial features such as small-scale oscillations in the initial matter power spectrum (as arise in models involving collisional effects in the dark sector), while being largely insensitive to a truncation of initial power (as in warm dark matter models). For vanilla cold dark matter (CDM) cosmologies, the summary statistics display strong evolution and redshift-space effects, and are also sensitive to cosmological parameter values for realistic tracer samples. Comparing the VVF of galaxies in the Galaxies & Mass Assembly (GAMA) survey with that of abundance-matched CDM (sub)haloes tentatively reveals environmental effects in GAMA beyond halo mass (modulo unmodelled satellite properties). Our exploratory analysis thus paves the way for using the VVF as a new probe of galaxy evolution physics as well as the nature of dark matter and dark energy.

Decoherence describes the tendency of quantum sub-systems to dynamically lose their quantum character. This happens when the quantum sub-system of interest interacts and becomes entangled with an environment that is traced out. For ordinary macroscopic systems, electromagnetic and other interactions cause rapid decoherence. However, dark matter (DM) may have the unique possibility of exhibiting naturally prolonged macroscopic quantum properties due to its weak coupling to its environment, particularly if it only interacts gravitationally. In this work, we compute the rate of decoherence for light DM in the galaxy, where a local density has its mass, size, and location in a quantum superposition. The decoherence is via the gravitational interaction of the DM overdensity with its environment, provided by ordinary matter. We focus on relatively robust configurations: DM perturbations that involve an overdensity followed by an underdensity, with no monopole, such that it is only observable at relatively close distances. We use non-relativistic scattering theory with a Newtonian potential generated by the overdensity to determine how a probe particle scatters off of it and thereby becomes entangled. As an application, we consider light scalar DM, including axions. In the galactic halo, we use diffuse hydrogen as the environment, while near the earth, we use air as the environment. For an overdensity whose size is the typical DM de Broglie wavelength, we find that the decoherence rate in the halo is higher than the present Hubble rate for DM masses m_a lesssim 5 × 10^-7 eV and in earth based experiments it is higher than the classical field coherence rate for m_a lesssim 10^-6 eV . When spreading of the states occurs, the rates can become much faster, as we quantify. Also, we establish that DM BECs decohere very rapidly and so are very well described by classical field theory.

For low-mass (frequency ≪GHz ) axions, dark matter detection experiments searching for an axion-photon-photon coupling generally have suppressed sensitivity, if they use a static background magnetic field. This geometric suppression can be alleviated by using a high-frequency oscillating background field. Here, we present a high-level sketch of such an experiment, using superconducting cavities at ∼GHz frequencies. We discuss the physical limits on signal power arising from cavity properties, and point out cavity geometries that could circumvent some of these limitations. We also consider how backgrounds, including vibrational noise and drive signal leakage, might impact sensitivity. While practical microwave field strengths are significantly below attainable static magnetic fields, the lack of geometric suppression, and higher quality factors, may allow superconducting cavity experiments to be competitive in some regimes.

We propose an approach to search for axion dark matter with a specially designed superconducting radio frequency cavity, targeting axions with masses m_a ≲ 10^-6 eV. Our approach exploits axion-induced transitions between nearly degenerate resonant modes of frequency ∼ GHz. A scan over axion mass is achieved by varying the frequency splitting between the two modes. Compared to traditional approaches, this allows for parametrically enhanced signal power for axions lighter than a GHz. The projected sensitivity covers unexplored parameter space for QCD axion dark matter for 10^-8 eV ≲ m_a ≲ 10^-6 eV and axion-like particle dark matter as light as m_a∼ 10^-14 eV.

We propose an effective field theory to describe hadrons with two heavy quarks without any assumption on the typical distance between the heavy quarks with respect to the typical hadronic scale. The construction is based on nonrelativistic QCD and inspired in the strong coupling regime of potential nonrelativistic QCD. We construct the effective theory at leading and next-to-leading order in the inverse heavy quark mass expansion for arbitrary quantum numbers of the light degrees of freedom. Hence our results hold for hybrids, tetraquarks, double heavy baryons and pentaquarks, for which we also present the corresponding operators at a nonrelativistic level. At leading order, the effective theory enjoys heavy quark spin symmetry and corresponds to the Born-Oppenheimer approximation. At next-to-leading order, spin and velocity-dependent terms arise, which produce splittings in the heavy quark spin symmetry multiplets. A concrete application to double heavy baryons is presented in an accompanying paper.

Primordial black holes formed through the collapse of cosmological density fluctuations have been hypothesized as contributors to the dark matter content of the Universe. At the same time, their mergers could contribute to the recently observed population of gravitational-wave sources. We investigate the scenario in which primordial black holes form binaries at late times in the Universe. Specifically, we re-examine the mergers of primordial black holes in small clusters of ∼30 objects in the absence of initial binaries. Binaries form dynamically through Newtonian gravitational interactions. These binaries act as heat sources for the cluster, increasing the cluster's velocity dispersion, which inhibits direct mergers through gravitational-wave two-body captures. Meanwhile, three-body encounters of tight binaries are too rare to tighten binaries sufficiently to allow them to merge through gravitational-wave emission. We conclude that in the absence of initial binaries, merger rates of primordial black holes in the considered scenario are at least an order of magnitude lower than previously suggested, which makes gravitational-wave detections of such sources improbable.

We perform a comprehensive study of collider aspects of a Higgs portal scenario that is protected by an unbroken Z₂ symmetry. If the mass of the Higgs portal scalar is larger than half the Higgs mass, this scenario becomes very difficult to detect. We provide a detailed investigation of the model's parameter space based on analyses of the direct collider sensitivity at the LHC as well as at future lepton and hadron collider concepts and analyse the importance of these searches for this scenario in the context of expected precision Higgs and electroweak measurements. In particular we also consider the associated electroweak oblique corrections that we obtain in a first dedicated two-loop calculation for comparisons with the potential of, e.g., GigaZ. The currently available collider projections corroborate an FCC-hh 100 TeV as a very sensitive tool to search for such a weakly-coupled Higgs sector extension, driven by small statistical uncertainties over a large range of energy coverage. Crucially, however, this requires good theoretical control. Alternatively, Higgs signal-strength measurements at an optimal FCC-ee sensitivity level could yield comparable constraints.

We study parametric instability of compact axion dark matter structures decaying to radiophotons. Corresponding objects—Bose (axion) stars, their clusters, and clouds of diffuse axions—form abundantly in the postinflationary Peccei-Quinn scenario. We develop general description of parametric resonance incorporating finite-volume effects, backreaction, axion velocities, and their (in)coherence. With additional coarse graining, our formalism reproduces kinetic equation for virialized axions interacting with photons. We derive conditions for the parametric instability in each of the above objects, as well as in collapsing axion stars, evaluate photon resonance modes and their growth exponents. As a by-product, we calculate stimulated emission of Bose stars and diffuse axions, arguing that the former can give larger contribution into the radio background. In the case of QCD axions, the Bose stars glow and collapsing stars radioburst if the axion-photon coupling exceeds the original Kim-Shifman-Vainshtein-Zakharov value by 2 orders of magnitude. The latter constraint is alleviated for several nearby axion stars in resonance and absent for axionlike particles. Our results show that the parametric effect may reveal itself in observations, from fast radio bursts to excess radio background.

We analyze the recent hints of lepton flavor universality violation in both charged-current and neutral-current rare decays of B mesons in an R -parity-violating supersymmetric scenario. Motivated by simplicity and minimality, we had earlier postulated the third-generation superpartners to be the lightest (calling the scenario "RPV3") and explicitly showed that it preserves gauge coupling unification and of course has the usual attribute of naturally addressing the Higgs radiative stability. Here we show that both R_D^(*) and R_K^(*) flavor anomalies can be addressed in this RPV3 framework. Interestingly, this scenario may also be able to accommodate two other seemingly disparate anomalies, namely, the longstanding discrepancy in the muon (g -2 ), as well as the recent anomalous upgoing ultrahigh-energy Antarctic Impulsive Transient Antenna events. Based on symmetry arguments, we consider three different benchmark points for the relevant RPV3 couplings and carve out the regions of parameter space where all (or some) of these anomalies can be simultaneously explained. We find it remarkable that such overlap regions exist, given the plethora of precision low-energy and high-energy experimental constraints on the minimal model parameter space. The third-generation superpartners needed in this theoretical construction are all in the 1-10 TeV range, accessible at the LHC and/or next-generation hadron colliders. We also discuss some testable predictions for the lepton-flavor-violating decays of the tau lepton and B mesons for the current and future B -physics experiments, such as LHCb and Belle II. Complementary tests of the flavor anomalies in the high-p_T regime in collider experiments such as the LHC are also discussed.

We review the landscape of QCD axion models. Theoretical constructions that extend the window for the axion mass and couplings beyond conventional regions are highlighted and classified. Bounds from cosmology, astrophysics and experimental searches are reexamined and updated.

We present a factorization theorem valid near the kinematic threshold z =Q²/s ̂→1 of the partonic Drell-Yan process q q ¯→γ^∗+X for general subleading powers in the (1 - z) expansion. We then consider the specific case of next-to-leading power. We discuss the emergence of collinear functions, which are a key ingredient to factorization starting at next-to-leading power. We calculate the relevant collinear functions at O (α_s) by employing an operator matching equation and we compare our results to the expansion-by- regions computation up to the next-to-next-to-leading order, finding agreement. Factorization holds only before the dimensional regulator is removed, due to a divergent convolution when the collinear and soft functions are first expanded around d = 4 before the convolution is performed. This demonstrates an issue for threshold resummation beyond the leading-logarithmic accuracy at next-to-leading power.

Massive dwarf galaxies that merge with the Milky Way on prograde orbits can be dragged into the disk plane before being completely disrupted. Such mergers can contribute to an accreted stellar disk and a dark matter disk. Here we present Nyx, a vast stellar stream in the vicinity of the Sun, which provides the first indication that such an event occurred in the Milky Way. We identify about 90 stars that have coherent radial and prograde motion in this stream using a catalogue of accreted stars built by applying deep learning methods to the Gaia data. Taken together with chemical abundance and orbital information, these results strongly favour the interpretation that Nyx is the remnant of a disrupted dwarf galaxy. Further justified by FIRE hydrodynamic simulations, we demonstrate that prograde streams like Nyx can be found in the disk plane of galaxies and identified using our methods.

We show how the properties of the QCD axion change in systems at finite baryonic density, such as neutron stars. At nuclear saturation densities, where corrections can be reliably computed, we find a mild reduction of the axion mass and up to an order of magnitude enhancement in the model-independent axion coupling to neutrons. At moderately higher densities, if realized, meson (kaon) condensation can trigger axion condensation. We also study the axion potential at asymptotically large densities, where the color-superconducting phase of QCD potentially leads to axion condensation, and the mass of the axion is generically several orders of magnitude smaller than in vacuum due to the suppressed instantons. Several phenomenological consequences of the axion being sourced by neutron stars are discussed, such as its contribution to their total mass, the presence of an axionic brane, or axion-photon conversion in the magnetosphere.

In this paper we present the complete one-loop matching conditions, up to dimension-six operators of the Standard Model effective field theory, resulting by integrating out the two scalar leptoquarks S₁∼("_{separators=",3 1 )1/3} and S₃∼("_{separators=",3 3 )1/3}. This allows a phenomenological study of low-energy constraints on this model at one-loop accuracy, which will be the focus of a subsequent work. Furthermore, it provides a rich comparison for functional and computational methods for one-loop matching, that are being developed. As a corollary result, we derive a complete set of dimension-six operators independent under integration by parts, but not under equations of motions, called Green's basis, as well as the complete reduction formulae from this set to the Warsaw basis.

Outflows driven by large-scale magnetic fields likely play an important role in the evolution and dispersal of protoplanetary disks and in setting the conditions for planet formation. We extend our 2D-axisymmetric nonideal MHD model of these outflows by incorporating radiative transfer and simplified thermochemistry, with the dual aims of exploring how heating influences wind launching and illustrating how such models can be tested through observations of diagnostic spectral lines. Our model disks launch magnetocentrifugal outflows primarily through magnetic tension forces, so the mass-loss rate increases only moderately when thermochemical effects are switched on. For typical field strengths, thermochemical and irradiation heating are more important than magnetic dissipation. We furthermore find that the entrained vertical magnetic flux diffuses out of the disk on secular timescales as a result of nonideal MHD. Through postprocessing line radiative transfer, we demonstrate that spectral line intensities and moment-1 maps of atomic oxygen, the HCN molecule, and other species show potentially observable differences between a model with a magnetically driven outflow and one with a weaker, photoevaporative outflow. In particular, the line shapes and velocity asymmetries in the moment-1 maps could enable the identification of outflows emanating from the disk surface.

Recent stacked ALMA observations have revealed that normal, star-forming galaxies at z ≈ 6 are surrounded by extended (≈10 kpc) [C II]-emitting haloes, which are not predicted by the most advanced, zoom-in simulations. We present a model in which these haloes are the result of supernova-driven cooling outflows. Our model contains two free parameters, the outflow mass loading factor, η, and the parent galaxy dark matter halo circular velocity, V_c. The outflow model successfully matches the observed [C II] surface brightness profile if η = 3.20 ± 0.10 and $v_{\rm c} = 170 \pm 10 \, \rm km\, s^{-1}$ , corresponding to a dynamical mass of ${\approx }10^{11}\, {\rm M}_{\odot }$ . The predicted outflow rate and velocity range are $128 \pm 5\, {\rm M}_{\odot }\, {\rm yr}^{-1}$ and 300-500 $\, \rm km\, s^{-1}$ , respectively. We conclude that (a) extended haloes can be produced by cooling outflows; (b) the large η value is marginally consistent with starburst-driven outflows, but it might indicate additional energy input from active galactic nuclei; and (c) the presence of [C II] haloes requires an ionizing photon escape fraction from galaxies f_esc ≪ 1. The model can be readily applied also to individual high-z galaxies, as those observed, e.g. by the ALMA ALPINE survey now becoming available.

We study perturbation theory for large-scale structure in the most general scalar-tensor theories propagating a single scalar degree of freedom, which include Horndeski theories and beyond. We model the parameter space using the effective field theory of dark energy. For Horndeski theories, the gravitational field and fluid equations are invariant under a combination of time-dependent transformations of the coordinates and fields. This symmetry allows one to construct a physical adiabatic mode which fixes the perturbation-theory kernels in the squeezed limit and ensures that the well-known consistency relations for large-scale structure, originally derived in general relativity, hold in modified gravity as well. For theories beyond Horndeski, instead, one generally cannot construct such an adiabatic mode. Because of this, the perturbation-theory kernels are modified in the squeezed limit and the consistency relations for large-scale structure do not hold. We show, however, that the modification of the squeezed limit depends only on the linear theory. We investigate the observational consequences of this violation by computing the matter bispectrum. In the squeezed limit, the largest effect is expected when considering the cross-correlation between different tracers. Moreover, the individual contributions to the 1-loop matter power spectrum do not cancel in the infrared limit of the momentum integral, modifying the power spectrum on nonlinear scales.

The accuracy of the Hubble constant measured with extragalactic Cepheids depends on robust photometry and background estimation in the presence of stellar crowding. The conventional approach accounts for crowding by sampling backgrounds near Cepheids and assuming that they match those at their positions. We show a direct consequence of crowding by unresolved sources at Cepheid sites is a reduction in the fractional amplitudes of their light curves. We use a simple analytical expression to infer crowding directly from the light curve amplitudes of >200 Cepheids in three Type Ia supernovae hosts and NGC 4258 as observed by Hubble Space Telescope—the first near-infrared amplitudes measured beyond the Magellanic Clouds. Where local crowding is minimal, we find near-infrared amplitudes match Milky Way Cepheids at the same periods. At greater stellar densities we find that the empirically measured amplitudes match the values predicted (with no free parameters) from crowding assessed in the conventional way from local regions, confirming their accuracy for estimating the background at the Cepheid locations. Extragalactic Cepheid amplitudes would need to be ∼20% smaller than measured to indicate additional, unrecognized crowding as a primary source of the present discrepancy in H₀. Rather, we find the amplitude data constrains a systematic mis-estimate of Cepheid backgrounds to be 0.029 ± 0.037 mag, more than 5× smaller than the size of the present ∼0.2 mag tension in H₀. We conclude that systematic errors in Cepheid backgrounds do not provide a plausible resolution to the Hubble tension.

The QCD axion provides an elegant solution to the strong C P problem. While the minimal realization is vulnerable to the so-called "axion quality problem," we will consider a more robust realization in the presence of a mirror sector related to the standard model by a (softly broken) Z₂ symmetry. We point out that the resulting "heavy" axion, while satisfying all theoretical and observational constraints, has a large and uncharted parameter space, which allows it to be probed at the LHC as a long-lived particle (LLP). The small defining axionic coupling to gluons results in a challenging hadronic decay signal which we argue can be distinguished against the background in such a long-lived regime, and yet, the same coupling allows for sufficient production at the hadron colliders thanks to the large gluon-parton luminosity. Our study opens up a new window towards accelerator observable axions and, more generally, singly produced LLPs.

We revisit techniques for performing cosmological simulations with both baryons and cold dark matter when each fluid has different initial conditions, as is the case at the end of the radiation era. Most simulations do not reproduce the linear prediction for the difference between the cold dark matter and baryon perturbations. We show that this is due to the common use of offset regular grids when setting up the particle initial conditions. The desired linear evolution can be obtained without any loss of simulation resolution by using a Lagrangian glass for the baryon particles. We further show that the difference between cold dark matter and baryons may affect predictions for the Lyman-α forest flux power spectrum at the 5% level, potentially impacting current cosmological constraints.

We use functional methods to compute one-loop effects in Heavy Quark Effective Theory. The covariant derivative expansion technique facilitates the efficient extraction of matching coefficients and renormalization group evolution equations. This paper pro- vides the first demonstration that such calculations can be performed through the algebraic evaluation of the path integral for the class of effective field theories that are (i) constructed using a non-trivial one-to-many mode decomposition of the UV theory, and (ii) valid for non-relativistic kinematics. We discuss the interplay between operators that appear at intermediate steps and the constraints imposed by the residual Lorentz symmetry that is encoded as reparameterization invariance within the effective description. The tools presented here provide a systematic approach for computing corrections to higher order in the heavy mass expansion; precision applications include predictions for experimental data and connections to theoretical tests via lattice QCD. A set of pedagogical appendices comprehensively reviews modern approaches to performing functional calculations algebraically, and derives contributions from a term with open covariant derivatives for the first time.

Early-type galaxies - slow and fast rotating ellipticals (E-SRs and E-FRs) and S0s/lenticulars - define a Fundamental Plane (FP) in the space of half-light radius R_e, enclosed surface brightness I_e, and velocity dispersion σ_e. Since I_e and σ_e are distance-independent measurements, the thickness of the FP is often expressed in terms of the accuracy with which I_e and σ_e can be used to estimate sizes R_e. We show that: (1) The thickness of the FP depends strongly on morphology. If the sample only includes E-SRs, then the observed scatter in R_e is ∼ 16 per cent, of which only ∼ 9 per cent is intrinsic. Removing galaxies with M_* < 10¹¹ M_⊙ further reduces the observed scatter to ∼ 13 per cent (∼ 4 per cent intrinsic). The observed scatter increases to ∼ 25 per cent usually quoted in the literature if E-FRs and S0s are added. If the FP is defined using the eigenvectors of the covariance matrix of the observables, then the E-SRs again define an exceptionally thin FP, with intrinsic scatter of only 5 per cent orthogonal to the plane. (2) The structure within the FP is most easily understood as arising from the fact that I_e and σ_e are nearly independent, whereas the R_e-I_e and R_e-σ_e correlations are nearly equal and opposite. (3) If the coefficients of the FP differ from those associated with the virial theorem the plane is said to be 'tilted'. If we multiply I_e by the global stellar mass-to-light ratio M_*/L and we account for non-homology across the population by using Sérsic photometry, then the resulting stellar mass FP is less tilted. Accounting self-consistently for M_*/L gradients will change the tilt. The tilt we currently see suggests that the efficiency of turning baryons into stars increases and/or the dark matter fraction decreases as stellar surface brightness increases.

In order to detect high frequency gravitational waves, we need a new detection method. In this paper, we develop a formalism for a gravitational wave detector using magnons in a cavity. Using Fermi normal coordinates and taking the non-relativistic limit, we obtain a Hamiltonian for magnons in gravitational wave backgrounds. Given the Hamiltonian, we show how to use the magnons for detecting high frequency gravitational waves. Furthermore, as a demonstration of the magnon gravitational wave detector, we give upper limits on GHz gravitational waves by utilizing known results of magnon experiments for an axion dark matter search.

We calculate the step-scaling function, the lattice analog of the renormalization group β -function, for an SU(3) gauge theory with ten fundamental flavors. We present a detailed analysis including the study of systematic effects of our extensive data set generated with ten dynamical flavors using the Symanzik gauge action and three times stout smeared Möbius domain wall fermions. Using up to 32⁴ volumes, we calculate renormalized couplings for different gradient flow schemes and determine the step-scaling β function for a scale change s =2 on up to five different lattice volume pairs. In an accompanying paper we discuss that gradient flow can promote lattice dislocations to instantonlike objects, introducing nonperturbative lattice artifacts to the step-scaling function. Motivated by the observation that Wilson flow sufficiently suppresses these artifacts, we choose Wilson flow with the Symanzik operator as our preferred analysis. We study systematic effects by calculating the step-scaling function based on alternative flows (Zeuthen or Symanzik), alternative operators (Wilson plaquette, clover), and also explore the effects of the perturbative tree-level improvement. Further we investigate the effects due to the finite value of L_s.

The Fundamental Plane (FP) of black hole (BH) activity in galactic nuclei relates X-ray and radio luminosities to BH mass and accretion rate. However, there is a large scatter exhibited by the data, which motivated us for a new variable. We add BH spin as a new variable and estimate the spin dependence of the jet power and disc luminosity in terms of radio and X-ray luminosities. We assume the Blandford-Znajek process as the main source of the outflow, and find that the jet power depends on BH spin stronger than quadratically at moderate and large spin values. We perform a statistical analysis for 10 active galactic nuclei (AGNs) which have sub-Eddington accretion rates and whose spin values are measured independently via the reflection or continuum-fitting methods, and find that the spin-dependent relation describes the data significantly better. This analysis, if supported with more data, could imply not only the spin dependence of the FP relation, but also the Blandford-Znajek process in AGN jets.

In the presence of an external magnetic field, the axion and the photon mix. In particular, the dispersion relation of a longitudinal plasmon always crosses the dispersion relation of the axion (for small axion masses), thus leading to a resonant conversion. Using thermal field theory, we concisely derive the axion emission rate, applying it to astrophysical and laboratory scenarios. For the Sun, depending on the magnetic field profile, plasmon-axion conversion can dominate over Primakoff production at low energies (≲200 eV ). This both provides a new axion source for future helioscopes and, in the event of discovery, would probe the magnetic field structure of the Sun. In the case of white dwarfs (WDs), plasmon-axion conversion provides a pure photon coupling probe of the axion, which may contribute significantly for low-mass WDs. Finally, we rederive and confirm the axion absorption rate of the recently proposed plasma haloscopes.

It has been argued that the symmetries of gravity at null infinity should include a Diff (S²) factor associated with diffeomorphisms on the celestial sphere. However, the standard phase space of gravity does not support the action of such transformations. Building on earlier work by Laddha and one of the authors, we present an extension of the phase space of gravity at null infinity on which Diff (S²) acts canonically. The Poisson brackets of supertranslation and Diff (S²) charges reproduce the generalized BMS algebra introduced in [Campiglia and Laddha Phys. Rev. D 90, 124028 (2014), 10.1103/PhysRevD.90.124028].

The relation between early type galaxy size, surface brightness and velocity dispersion, ``the fundamental plane", has long been understood as resulting from equilibrium in their largely pressure supported stellar dynamics. The dissipation and feedback involved in reaching such an equilibrium through merger formation of these galaxies over cosmic time can be responsible for the orientation of the plane. We see a correlation between surface brightness enhancement and youth in the 6dF Galaxy Survey. Correlations of this `tilt' with stellar mass, age, concentration, shape and metallicity now point the direction for further work on the resolved kinematics and structure of these nearby galaxies and on their initial mass function and dark matter component. On the face of it, the Tully Fisher relation is a simpler one dimensional scaling relation. However, as late type galaxies have bulges as well as disks, and, as the surface density of disks is only standard for the more massive galaxies, additional parameters are involved.

We study the K ¯ p →Y K K ¯ π reactions with K ¯ =K^{¯ 0},K^- and Y =Σ⁰,Σ⁺,Λ , in the region of K K ¯ π invariant masses of 1200 -1550 MeV. The strong coupling of the f₁(1285 ) resonance to K^∗K ¯ makes the mechanism based on K^∗ exchange very efficient to produce this resonance observed in the K K ¯ π invariant mass distribution. In addition, in all these reactions one observes an associated peak at 1420 MeV which comes from the K^∗K ¯ decay mode of the f₁(1285 ) when the K^∗ is placed on shell at higher invariant masses. We call the attention to the possibility that the peaks observed in other reactions where the "f₁(1420 ) " is observed have a similar origin.

We calculate the masses of χ_c(3 P ) states with threshold corrections in a coupled-channel model. The model was recently applied to the description of the properties of χ_c(2 P ) and χ_b(3 P ) multiplets (Ferretti and Santopinto in Phys Lett B 789:550, 2019]. We also compute the open-charm strong decay widths of the χ_c(3 P ) states and their radiative transitions. According to our predictions, the χ_c(3 P ) states should be dominated by the charmonium core, but they may also show small meson-meson components. The X(4274) is interpreted as a c c ¯ χ_{c 1}(3 P ) state. More information on the other members of the χ_c(3 P ) multiplet, as well as a more rigorous analysis of the X(4274)'s decay modes, are needed to provide further indications on the quark structure of the previous resonance.

Vector leptoquarks can address the lepton flavor universality anomalies in decays associated with the b → cℓν and b → sℓℓ transitions, as observed in recent years. While not required to explain the anomalies, these leptoquarks generically yield new sources of CP violation. In this paper, we explore constraints and discovery potential for electric dipole moments (EDMs) in leptonic and hadronic systems. We provide the most generic expressions for dipole moments induced by vector leptoquarks at one loop. We find that O(1) CP-violating phases in tau and muon couplings can lead to corresponding EDMs within reach of next-generation EDM experiments, and that existing bounds on the electron EDM already put stringent constraints on CP-violating electron couplings.

We estimate the H I mass function (HIMF) of galaxies in groups based on thousands of ALFALFA (Arecibo Legacy Fast ALFA survey) H I detections within the galaxy groups of four widely used SDSS (Sloan Digital Sky Survey) group catalogues. Although differences between the catalogues mean that there is no one definitive group galaxy HIMF, in general we find that the low-mass slope is flat, in agreement with studies based on small samples of individual groups, and that the 'knee' mass is slightly higher than that of the global HIMF of the full ALFALFA sample. We find that the observed fraction of ALFALFA galaxies in groups is approximately 22 per cent. These group galaxies were removed from the full ALFALFA source catalogue to calculate the field HIMF using the remaining galaxies. Comparison between the field and group HIMFs reveals that group galaxies make only a small contribution to the global HIMF as most ALFALFA galaxies are in the field, but beyond the HIMF 'knee' group galaxies dominate. Finally, we attempt to separate the group galaxy HIMF into bins of group halo mass, but find that too few low-mass galaxies are detected in the most massive groups to tightly constrain the slope, owing to the rarity of such groups in the nearby Universe where low-mass galaxies are detectable with existing H I surveys.

We present accurate measurements of the total H I mass in dark matter halos of different masses at z ∼ 0, by stacking the H I spectra of entire groups from the Arecibo Fast Legacy ALFA Survey. The halos are selected from the optical galaxy group catalog constructed from the Sloan Digital Sky Survey DR7 Main Galaxy sample, with reliable measurements of halo mass and halo membership. We find that the H I-halo mass relation is not a simple monotonic function, as assumed in several theoretical models. In addition to the dependence of halo mass, the total H I gas mass shows a strong dependence on the halo richness, with larger H I masses in groups with more members at fixed halo masses. Moreover, halos with at least three member galaxies in the group catalog have a sharp decrease of the H I mass, potentially caused by the virial halo shock-heating and the active galactic nucleus (AGN) feedback. The dominant contribution of the H I gas comes from the central galaxies for halos of ${M}_{{\rm{h}}}\lt {10}^{12.5}{h}^{-1}{M}_{\odot }$ , while the satellite galaxies dominate over more massive halos. Our measurements are consistent with a three-phase formation scenario of the H I-rich galaxies. The smooth cold gas accretion is driving the H I mass growth in halos of ${M}_{{\rm{h}}}\lt {10}^{11.8}{h}^{-1}{M}_{\odot }$ , with late-forming halos having more H I accreted. The virial halo shock-heating and AGN feedback will take effect to reduce the H I supply in halos of ${10}^{11.8}{h}^{-1}{M}_{\odot }\lt {M}_{{\rm{h}}}\lt {10}^{13}{h}^{-1}{M}_{\odot }$ . The H I mass in halos more massive than ${10}^{13}{h}^{-1}{M}_{\odot }$ generally grows by mergers, with the dependence on halo richness becoming much weaker.

Star-forming galaxies with strong nebular and collisional emission lines are privileged target galaxies in forthcoming cosmological large galaxy redshift surveys. We use the COSMOS2015 photometric catalogue to model galaxy spectral energy distributions and emission-line fluxes. We adopt an empirical but physically motivated model that uses information from the best-fitting spectral energy distribution of stellar continuum to each galaxy. The emission-line flux model is calibrated and validated against direct flux measurements in subsets of galaxies that have 3D-HST or zCOSMOS-Bright spectra. We take a particular care in modelling dust attenuation such that our model can explain both Hα and [O II] observed fluxes at different redshifts. We find that a simple solution to this is to introduce a redshift evolution in the dust attenuation fraction parameter, f = E_star(B - V)/E_gas(B - V), as f(z) = 0.44 + 0.2z. From this catalogue, we derive the Hα and [O II] luminosity functions up to redshifts of about 2.5 after carefully accounting for emission line flux and redshift errors. This allows us to make predictions for Hα and [O II] galaxy number counts in next-generation cosmological redshift surveys. Our modelled emission lines and spectra in the COSMOS2015 catalogue shall be useful to study the target selection for planned next-generation galaxy redshift surveys and we make them publicly available as 'EL-COSMOS' on the ASPIC data base.

Ultralight bosonic fields are compelling dark-matter candidates and arise in a variety of beyond standard model scenarios. These fields can tap energy and angular momentum from spinning black holes through superradiant instabilities, during which a macroscopic bosonic condensate develops around the black hole. Striking features of this phenomenon include gaps in the spin-mass distribution of astrophysical black holes and a continuous gravitational-wave (GW) signal emitted by the condensate. So far these processes have been studied in great detail for scalar fields and, more recently, for vector fields. Here we take an important step forward in the black hole superradiance program by computing, analytically, the instability timescale, direct GW emission, and stochastic background, in the case of massive tensor (i.e., spin-2) fields. Our analysis is valid for any black hole spin and for small boson masses. The instability of massive spin-2 fields shares some properties with the scalar and vector cases, but its phenomenology is much richer, for example, there exist multiple modes with comparable instability timescales, and the dominant GW signal is hexadecapolar rather than quadrupolar. Electromagnetic and GW observations of spinning black holes in the mass range M ∈(1 ,10¹⁰) M_⊙ can constrain the mass of a putative spin-2 field in the range 10^-22≲m_b c²/eV ≲10^-10 . For 10^-17≲m_b c²/eV ≲10^-15 , the space mission LISA could detect the continuous GW signal for sources at redshift z =20 , or even larger.

We present the conformal freeze-in (COFI) scenario for dark matter production. At high energies, the dark sector is described by a gauge theory flowing toward a Banks-Zaks fixed point, coupled to the Standard Model via a nonrenormalizable portal interaction. In the early Universe, a nonthermal freeze-in process transfers energy from the standard model plasma to the dark sector. During the freeze-in, the dark sector is described by a strongly coupled conformal field theory. As the Universe cools, cosmological phase transitions in the Standard Model sector, either electroweak or QCD, induce conformal symmetry breaking and confinement in the dark sector. One of the resulting dark bound states is stable on the cosmological time scales and plays the role of dark matter. With the Higgs portal, the COFI scenario provides a viable dark matter candidate with mass in a phenomenologically interesting sub-MeV range. With the quark portal, a dark matter candidate with mass around 1 keV is consistent with observations. Conformal bootstrap may put a nontrivial constraint on model building in this case.

We present the analytic form of the two-loop four-graviton scattering amplitudes in Einstein gravity. To remove ultraviolet divergences we include counterterms quadratic and cubic in the Riemann curvature tensor. The two-loop numerical unitarity approach is used to deal with the challenging momentum dependence of the interactions. We exploit the algebraic properties of the integrand of the amplitude in order to reduce it to a minimal basis of Feynman integrals. Analytic expressions are obtained from numerical evaluations of the amplitude. Finally, we show that four-graviton scattering observables depend on fewer couplings than naïvely expected.

In this Letter, we investigate the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing, we show that this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing, or even eliminating, the friction due to Hubble expansion. We highlight this phenomenon with a few examples. In the first example, we show how an axionlike particle can have its number abundance parametrically enhanced. In the second example, we demonstrate that the QCD axion can have its number abundance enhanced allowing for misalignment driven axion dark matter all the way down to f_a of order astrophysical bounds. In the third example, we show that the delayed oscillation of the scalar field can also sustain a period of inflation. In the last example, we present a situation where an oscillating scalar field is completely frictionless and does not dilute away in time.

We review the bootstrap method for constructing six- and seven-particle amplitudes in planar $\mathcal{N}=4$ super Yang-Mills theory, by exploiting their analytic structure. We focus on two recently discovered properties which greatly simplify this construction at symbol and function level, respectively: the extended Steinmann relations, or equivalently cluster adjacency, and the coaction principle. We then demonstrate their power in determining the six-particle amplitude through six and seven loops in the NMHV and MHV sectors respectively, as well as the symbol of the NMHV seven-particle amplitude to four loops.

We present cosmological parameter measurements from the publicly available Baryon Oscillation Spectroscopic Survey (BOSS) data on anisotropic galaxy clustering in Fourier space. Compared to previous studies, our analysis has two main novel features. First, we use a complete perturbation theory model that properly takes into account the non-linear effects of dark matter clustering, short-scale physics, galaxy bias, redshift-space distortions, and large-scale bulk flows. Second, we employ a Markov-Chain Monte-Carlo technique and consistently reevaluate the full power spectrum likelihood as we scan over different cosmologies. Our baseline analysis assumes minimal ΛCDM, varies the neutrino masses within a reasonably tight range, fixes the primordial power spectrum tilt, and uses the big bang nucleosynthesis prior on the physical baryon density ω_b. In this setup, we find the following late-Universe parameters: Hubble constant H₀=(67.9± 1.1) km s^-1Mpc^-1, matter density fraction Ω_m=0.295± 0.010, and the mass fluctuation amplitude σ₈=0.721± 0.043. These parameters were measured directly from the BOSS data and independently of the Planck cosmic microwave background observations. Scanning over the power spectrum tilt or relaxing the other priors do not significantly alter our main conclusions. Finally, we discuss the information content of the BOSS power spectrum and show that it is dominated by the location of the baryon acoustic oscillations and the power spectrum shape. We argue that the contribution of the Alcock-Paczynski effect is marginal in ΛCDM, but becomes important for non-minimal cosmological models.

We perform an updated fit to LHC Higgs data and LEP electroweak precision tests in the framework of the Standard Model Effective Field Theory (SMEFT). We assume a generic structure of the SMEFT operators without imposing any flavour symmetries. The implementation is released as part of the public global SMEFT likelihood. This allows one to fit parameters of a broad class of new physics models to combined Higgs, electroweak, quark flavour, and lepton flavour observables.

In [1], two of the present authors along with P. Raman attempted to extend the Amplituhedron program for scalar field theories [2] to quartic scalar interactions. In this paper we develop various aspects of this proposal. Using recent seminal results in Representation theory [3, 4], we show that projectivity of scattering forms and existence of kinematic space associahedron completely capture planar amplitudes of quartic interaction. We generalise the results of [1] and show that for any n-particle amplitude, the positive geometry associated to the projective scattering form is a convex realisation of Stokes polytope which can be naturally embedded inside one of the ABHY associahedra defined in [2, 5]. For a special class of Stokes polytopes with hyper-cubic topology, we show that they have a canonical convex realisation in kinematic space as boundaries of kinematic space associahedra. We then use these kinematic space geometric constructions to write world-sheet forms for

It is a common belief that the last missing piece of the Standard Model of particles physics was found with the discovery of the Higgs boson at the Large Hadron Collider. However, there remains a major prediction of quantum tunnelling processes mediated by instanton solutions in the Yang-Mills theory, that is still untested in the Standard Model. The direct experimental observation of instanton-induced processes, which are a consequence of the non-trivial vacuum structure of the Standard Model and of quantum tunnelling in QFT, would be a major breakthrough in modern particle physics. In this paper, we present for the first time a full calculation of QCD instanton-induced processes in proton-proton collisions accounting for quantum corrections due to both initial and final state gluon interactions, a first implementation in an MC event generator as well as a basic strategy how to observe these effects experimentally.

We consider which is the maximum information measurable from the decay distributions of polarised baryon decays via amplitude analysis in the helicity formalism. We focus in particular on the analytical study of the $\Lambda^+_c \to pK^-\pi^+$ decay distributions, demonstrating that the full information on its decay amplitudes can be extracted from its distributions, allowing a simultaneous measurement of both helicity amplitudes and the polarisation vector. This opens the possibility to use the $\Lambda^+_c \to pK^-\pi^+$ decay for applications ranging from New Physics searches to low-energy QCD studies, in particular its use as absolute polarimeter for the $\Lambda^+_c$ baryon. This result is valid as well for baryon decays having the same spin structure and it is cross-checked numerically by means of a toy amplitude fit with Monte Carlo pseudo-data.

We present an analysis of morphological, kinematic, and spectral asymmetries in observations of atomic neutral hydrogen (H I) gas from the Local Volume H I Survey (LVHIS), the VLA Imaging of Virgo in Atomic Gas (VIVA) survey, and the Hydrogen Accretion in Local Galaxies Survey. With the aim of investigating the impact of the local environment density and stellar mass on the measured H I asymmetries in future large H I surveys, we provide recommendations for the most meaningful measures of asymmetry for use in future analysis. After controlling for stellar mass, we find signs of statistically significant trends of increasing asymmetries with local density. The most significant trend we measure is for the normalized flipped spectrum residual (A_spec), with mean LVHIS and VIVA values of 0.204 ± 0.011 and 0.615 ± 0.068 at average weighted 10th nearest-neighbour galaxy number densities of log (ρ₁₀/Mpc^-3) = -1.64 and 0.88, respectively. Looking ahead to the Widefield ASKAP L-band Legacy All-sky Blind survey on the Australian Square Kilometre Array Pathfinder, we estimate that the number of detections will be sufficient to provide coverage over 5 orders of magnitude in both local density and stellar mass increasing the dynamic range and accuracy with which we can probe the effect of these properties on the asymmetry in the distribution of atomic gas in galaxies.

A complete one-loop matching calculation for real singlet scalar extensions of the Standard Model to the Standard Model effective field theory (SMEFT) of dimension- six operators is presented. We compare our analytic results obtained by using Feynman diagrams to the expressions derived in the literature by a combination of the universal one-loop effective action (UOLEA) approach and Feynman calculus. After identifying contributions that have been overlooked in the existing calculations, we find that the pure diagrammatic approach and the mixed method lead to identical results. We highlight some of the subtleties involved in computing one-loop matching corrections in SMEFT.

Aims: The goal of this study is to present the development of a machine learning based approach that utilizes phase space alone to separate the Gaia DR2 stars into two categories: those accreted onto the Milky Way from those that are in situ. Traditional selection methods that have been used to identify accreted stars typically rely on full 3D velocity, metallicity information, or both, which significantly reduces the number of classifiable stars. The approach advocated here is applicable to a much larger portion of Gaia DR2.
Methods: A method known as "transfer learning" is shown to be effective through extensive testing on a set of mock Gaia catalogs that are based on the FIRE cosmological zoom-in hydrodynamic simulations of Milky Way-mass galaxies. The machine is first trained on simulated data using only 5D kinematics as inputs and is then further trained on a cross-matched Gaia/RAVE data set, which improves sensitivity to properties of the real Milky Way.
Results: The result is a catalog that identifies ∼767 000 accreted stars within Gaia DR2. This catalog can yield empirical insights into the merger history of the Milky Way and could be used to infer properties of the dark matter distribution.

The baryon acoustic oscillations feature (BAO) imprinted in the clustering correlation function is known to furnish us cosmic distance determinations that are independent of the cosmological-background model and the primordial perturbation parameters. These measurements can be accomplished rigorously by means of the purely geometric BAO methods. To date two different purely geometric BAO approaches have been proposed. The first exploits the linear-point standard ruler. The second, called correlation-function model-fitting, exploits the sound-horizon standard ruler. A key difference between them is that, when estimated from clustering data, the linear point makes use of a cosmological-model-independent procedure to extract the ratio of the ruler to the cosmic distance, while the correlation-function model-fitting relies on a phenomenological cosmological model for the correlation function. Nevertheless the two rulers need to be precisely defined independently of any specific observable (e.g., the BAO). We define the linear point and sound horizon and we fully characterize and compare the two rulers' cosmological-parameter dependence. We find that they are both geometrical (i.e., independent of the primordial cosmological parameters) within the required accuracy, and that they have the same parameter dependence for a wide range of parameter values. We estimate the rulers' best-fit values and errors, given the cosmological constraints obtained by the Planck Satellite team from their measurements of the cosmic microwave background temperature and polarization anisotropies. We do this for three different cosmological models encompassed by the purely geometric BAO methods. In each case we find that the relative errors of the two rulers coincide and they are insensitive to the assumed cosmological model. Interestingly both the linear point and the sound horizon shift by 0.5 σ when we do not fix the spatial geometry to be flat in Λ CDM . This points toward a sensitivity of the rulers to different cosmological models when they are estimated from the cosmic microwave background.

The quality of the recent GlueX J /ψ photoproduction data from Hall D at Jefferson Laboratory and the proximity of the data to the energy threshold, gives access to a variety of interesting physics aspects. As an example, an estimation of the J /ψ -nucleon scattering length α_{J /ψ p} is provided within the vector meson dominance model. It results in | α_{J /ψ p}|=(3.08 ±0.55 (stat . ) ±0.42 (syst . ) ) mfm which is much smaller than a typical size of a hadron.

We have studied the small-scale distribution of atomic hydrogen (H I) using 21 cm absorption spectra against multiple-component background radio continuum sources from the 21-SPONGE survey and the Millennium Arecibo Absorption-Line Survey. We have found >5σ optical depth variations at a level of ∼0.03-0.5 between 13 out of 14 adjacent sightlines separated by a few arcseconds to a few arcminutes, suggesting the presence of neutral structures on spatial scales from a few to thousands of au (which we refer to as tiny-scale atomic structure, TSAS). The optical depth variations are strongest in directions where the H I column density and the fraction of H I in the cold neutral medium (CNM) are highest, which tend to be at low Galactic latitudes. By measuring changes in the properties of Gaussian components fitted to the absorption spectra, we find that changes in both the peak optical depth and the linewidth of TSAS absorption features contribute to the observed optical depth variations, while changes in the central velocity do not appear to strongly impact the observed variations. Both thermal and turbulent motions contribute appreciably to the linewidths, but the turbulence does not appear strong enough to confine overpressured TSAS. In a majority of cases, the TSAS column densities are sufficiently high that these structures can radiatively cool fast enough to maintain thermal equilibrium with their surroundings, even if they are overpressured. We also find that a majority of TSAS is associated with the CNM. For TSAS in the direction of the Taurus molecular cloud and the local Leo cold cloud, we estimate densities over an order of magnitude higher than typical CNM densities.

We examine the contribution of small instantons to the axion mass in various UV completions of QCD. We show that the reason behind the potential dominance of such contributions is the non-trivial embedding of QCD into the UV theory. The effects from instantons in the partially broken gauge group appear as "fractional instanton" corrections in the effective theory. These will exhibit unusual dependences on the various scales in the problem whenever the index of embedding is non-trivial. We present a full one-instanton calculation of the axion mass in the simplest product group models, carefully keeping track of numerical prefactors. Rather than using a 't Hooft operator approximation we directly evaluate the contributions to the vacuum bubble, automatically capturing the effects of closing up external fermion lines with Higgs loops. This approach is manifestly finite and removes the uncertainty associated with introducing a cutoff scale for the Higgs loops. We verify that the small instantons may dominate over the QCD contribution for very high breaking scales and at least three group factors.

Polarizations of primordial gravitational waves can be relevant when considering inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch-Davies vacuum. Instead of taking into account dynamical generation of polarizations of gravitational waves, in this paper, we consider polarized initial states constructed from $SU(2)$ coherent states. We then evaluate the power spectrums of the primordial gravitational waves in the states.

We study radial oscillations of non-rotating neutron stars (NSs) in four-dimensional general relativity. The interior of the NS was modeled within a recently proposed multicomponent realistic equation of state (EoS) with the induced surface tension (IST). In particular, we considered the IST EoS with two sets of model parameters, that both reproduce all the known properties of normal nuclear matter, give a high quality description of the proton flow constraint, hadron multiplicities created in nuclear-nuclear collisions, consistent with astrophysical observations and the observational data from the NS-NS merger. We computed the 12 lowest radial oscillation modes, their frequencies and corresponding eigenfunctions, as well as the large frequency separation for six selected fiducial NSs (with different radii and masses of 1.2, 1.5 and 1.9 solar masses) of the two distinct model sets. The calculated frequencies show their continuous growth with an increase of the NS central baryon density. Moreover, we found correlations between the behavior of the first eigenfunction calculated for the fundamental mode, the adiabatic index and the speed of sound profile, which could be used to probe the internal structure of NSs with the asteroseismology data.

The forthcoming generation of galaxy redshift surveys will sample the large-scale structure of the Universe over unprecedented volumes with high-density tracers. This advancement will make robust measurements of three-point clustering statistics possible. In preparation for this improvement, we investigate how several methodological choices can influence inferences based on the bispectrum about galaxy bias and shot noise. We first measure the real-space bispectrum of dark-matter haloes extracted from 298 N-body simulations covering a volume of approximately 1000 Gpc³. We then fit a series of theoretical models based on tree-level perturbation theory to the numerical data. To achieve this, we estimate the covariance matrix of the measurement errors by using 10,000 mock catalogues generated with the PINOCCHIO code. We study how the model constraints are influenced by the binning strategy for the bispectrum configurations and by the form of the likelihood function. We also use Bayesian model-selection techniques to single out the optimal theoretical description of our data. We find that a three-parameter bias model combined with Poissonian shot noise is necessary to model the halo bispectrum up to scales of k_maxlesssim 0.08 Mpc^-1, although fitting formulae that relate the bias parameters can be helpful to reduce the freedom of the model without compromising accuracy. Our data clearly disfavour local Eulerian and local Lagrangian bias models and do not require corrections to Poissonian shot noise. We anticipate that model-selection diagnostics will be particularly useful to extend the analysis to smaller scales as, in this case, the number of model parameters will grow significantly large.

Context. X-ray- and extreme ultraviolet (XEUV) driven photoevaporative winds acting on protoplanetary disks around young T Tauri stars may crucially impact disk evolution, affecting both gas and dust distributions.
Aims: We investigate the dust entrainment in XEUV-driven photoevaporative winds and compare our results to existing magnetohydrodynamic and EUV-only models.
Methods: We used a 2D hydrodynamical gas model of a protoplanetary disk irradiated by both X-ray and EUV spectra from a central T Tauri star to trace the motion of passive Lagrangian dust grains of various sizes. The trajectories were modelled starting at the disk surface in order to investigate dust entrainment in the wind.
Results: For an X-ray luminosity of L_X = 2 × 10³⁰ erg s^-1 emitted by a M_* = 0.7 M_⊙ star, corresponding to a wind mass-loss rate of Ṁ_w ≃ 2.6 × 10^-8 M_⊙ yr^-1, we find dust entrainment for sizes a₀ ≲ 11 μm (9 μm) from the inner 25 AU (120 AU). This is an enhancement over dust entrainment in less vigorous EUV-driven winds with Ṁ_w ≃ 10^-10 M_⊙ yr^-1. Our numerical model also shows deviations of dust grain trajectories from the gas streamlines even for μm-sized particles. In addition, we find a correlation between the size of the entrained grains and the maximum height they reach in the outflow.
Conclusions: X-ray-driven photoevaporative winds are expected to be dust-rich if small grains are present in the disk atmosphere.

We calculate a new contribution to the axion mass that arises from gluons propagating in a 5th dimension at high energies. By uplifting the 4D instanton solution to five dimensions, the positive frequency modes of the Kaluza-Klein states generate a power-law term in the effective action that inversely grows with the instanton size. This causes 5D small instantons to enhance the axion mass in a way that does not spoil the axion solution to the strong CP problem. Moreover this enhancement can be much larger than the usual QCD contribution from large instantons, although it requires the 5D gauge theory to be near the non-perturbative limit. Thus our result suggests that the mass range of axions (or axion-like particles), which is important for ongoing experimental searches, can depend sensitively on the UV modification of QCD.

QCD exhibits complex dynamics near S-wave two-body thresholds. For light mesons, we see this in the failure of quark models to explain the f₀ (500) and K₀^* (700) masses. For charmonium, an unexpected X (3872) state appears at the open charm threshold. In heavy-light systems, analogous threshold effects appear for the lowest J^P =0⁺ and 1⁺ states in the D_s and B_s systems. Here we describe how lattice QCD can be used to understand these threshold dynamics by smoothly varying the strange-quark mass when studying the heavy-light systems. Small perturbations around the physical strange quark mass are used so to always remain near the physical QCD dynamics. This calculation is a straightforward extension of those already in the literature and can be undertaken by multiple lattice QCD collaborations with minimal computational cost.

Inelastic dark matter and strongly interacting dark matter are poorly constrained by direct detection experiments since they both require the scattering event to deliver energy from the nucleus into the dark matter in order to have observable effects. We propose to test these scenarios by searching for the collisional deexcitation of metastable nuclear isomers by the dark matter particles. The longevity of these isomers is related to a strong suppression of γ - and β -transitions, typically inhibited by a large difference in the angular momentum for the nuclear transition. The collisional deexcitation by dark matter is possible since heavy dark matter particles can have a momentum exchange with the nucleus comparable to the inverse nuclear size, hence lifting tremendous angular momentum suppression of the nuclear transition. This deexcitation can be observed either by searching for the direct effects of the decaying isomer, or through the rescattering or decay of excited dark matter states in a nearby conventional dark matter detector setup. Existing nuclear isomer sources such as naturally occurring ^Tam₁₈₀ , ^Bam₁₃₇ produced in decaying Cesium in nuclear waste, ^Lum₁₇₇ from medical waste, and ^Hfm₁₇₈ from the Department of Energy storage can be combined with current dark matter detector technology to search for this class of dark matter.