If dark matter annihilates into standard model particles with a cross section which is velocity dependent, then Local Group dwarf galaxies will not be the best place to search for the resulting gamma ray emission. A greater flux would be produced by more distant and massive halos, with larger velocity dispersions. We construct full-sky predictions for the gamma ray emission from galaxy- and cluster-mass halos within $\sim 200\mathrm{Mpc}$ using a suite of constrained $N$-body simulations (CSiBORG) based on the Bayesian Origin Reconstruction from Galaxies algorithm. Comparing to observations from the Fermi Large Area Telescope and marginalizing over reconstruction uncertainties and other astrophysical contributions to the flux, we obtain constraints on the cross section which are 2 (7) orders of magnitude tighter than those obtained from dwarf spheroidals for $p$-wave ($d$-wave) annihilation. We find no evidence for either type of annihilation from dark matter particles with masses in the range $m_{\chi }=2–500\mathrm{GeV}/c^2$, for any channel. As an example, for annihilations producing bottom quarks with $m_{\chi }=10\mathrm{GeV}/c^2$, we find $a_1<2.4\times {10}^{-21}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ and $a_2<3.0\times {10}^{-18}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 95% confidence, where the product of the cross section, $\sigma$, and relative particle velocity, $v$, is given by $\sigma v=a_{\ell }(v/c{)}^{2\ell }$ and $\ell =1$, 2 for $p$- and $d$-wave annihilation, respectively. Our bounds, although failing to exclude the thermal relic cross section for velocity-dependent annihilation channels, are among the tightest to date.

We present a $9.3\sigma$ detection of the pairwise kinematic Sunyaev-Zel’dovich (kSZ) effect by combining a sample of 913,286 Luminous Red Galaxies (LRGs) from the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) catalog and coadded Atacama Cosmology Telescope (ACT DR6) and Planck cosmic microwave background (CMB) temperature maps. This represents the highest-significance pairwise kSZ measurement to date. The analysis uses three ACT CMB temperature maps: coadded 150 GHz, total frequency maps, and a component separated Internal Linear Combination (ILC) map, all of which cover 19,000 square degrees of the sky from Advanced ACTPol observations conducted between 2017 and 2022. Comparison of the results of these three maps serves as a consistency check for potential foreground contamination that may depend on the observation frequency. An estimate of the best-fit mass-averaged optical depth is obtained by comparing the pairwise kSZ curve with the linear theory prediction of the pairwise velocity under the best-fit Planck cosmology and is compared with predictions from simulations. This estimate serves as a reference point for future comparisons with thermal SZ–derived optical depth measurements for the same DESI cluster samples, which will be presented in a companion paper. Finally, we employ a machine learning approach, trained on simulations to estimate the optical depth for 456,803 DESI LRG-identified clusters within the simulated mass range ($\gtrsim {10}^{13}{M}_{\odot }$). These are combined with the measured kSZ signal to infer the individual cluster peculiar velocities, providing the opportunity to constrain the behavior of gravity and the dark sector over a range of cosmic scales and epochs.

We investigate the velocity-dependent one-scale model to the case of one cosmic F-string and two D-strings as color flux tubes in pure Spin($4N$) gauge theory. We analytically calculate the scaling string density as a function of the reconnection probabilities, and confirm our results with numerical calculations. We also determine the timescale at which the string density reaches the scaling regime, and find that for certain values of the reconnection probability, the scaling time can become extremely large, by many orders of magnitude. This leads to a characteristic suppression signature of the gravitational-wave signal at high frequencies, which may become observable in the frequency range of future interferometric gravitational-wave observations.

We present forecasts for constraints on the matter density (${\mathrm{\Omega }}_m$) and the amplitude of matter density fluctuations at $8{\mathrm{h}}^{-1}\mathrm{Mpc}$ (${\sigma }_8$) from cosmic microwave background lensing convergence (${\kappa }_{\mathrm{CMB}}$) maps and galaxy weak lensing convergence (${\kappa }_{\mathrm{WL}}$) maps. For ${\kappa }_{\mathrm{CMB}}$ auto statistics, we compare the angular power spectra ($C_{\ell }$’s) to the wavelet scattering transform (WST) coefficients. For ${\kappa }_{\mathrm{CMB}}\times {\kappa }_{\mathrm{WL}}$ statistics, we compare the cross angular power spectra to wavelet phase harmonics (WPH). This work also serves as the first application of WST and WPH to these probes. For ${\kappa }_{\mathrm{CMB}}$, we find that WST and $C_{\ell }$’s yield similar constraints in forecasts for all surveys considered in this work. When ${\kappa }_{\mathrm{CMB}}$ is crossed with ${\kappa }_{\mathrm{WL}}$ projected from Euclid Data Release 2, we find that WPH outperforms cross-$C_{\ell }$’s by factors between 2.2 and 3.4 for individual parameter constraints. To compare these different summary statistics, we develop a novel learned binning approach. This method compresses summary statistics while maintaining interpretability. We find this leads to improved constraints compared to more naive binning schemes for our wavelet-based statistics, but not for $C_{\ell }$’s. By learning the binning and measuring constraints on distinct datasets, our method is robust to overfitting by construction.

The gravitational collapse of collisionless matter leads to shell-crossing singularities that challenge the applicability of standard perturbation theory. Here, we present the first fully perturbative approach in three dimensions by using Lagrangian coordinates that asymptotically captures the highly nonlinear nature of matter evolution after the first shell crossing. This is made possible essentially thanks to two basic ingredients: (i) We employ high-order standard Lagrangian perturbation theory to evolve the system until shell crossing, and (ii) we exploit the fact that the density caustic structure near the first shell crossing begins generically with pancake formation. The latter property allows us to exploit largely known one-dimensional results to determine perturbatively the gravitational backreaction after collapse, yielding accurate solutions within our postcollapse perturbation theory (PCPT) formalism. We validate the PCPT predictions against high-resolution Vlasov-Poisson simulations and demonstrate that PCPT provides a robust framework for describing the early stages of postcollapse dynamics.

We present an independent calibration of the photometric redshift (photo-$z$) distributions for source galaxies in the Hyper Suprime-Cam year 3 (HSC Y3) weak lensing survey using small-scale galaxy-galaxy lensing. By measuring the tangential shear around spectroscopic lens galaxies from Galaxy and Mass Assembly, Sloan Digital Sky Survey, and Dark Energy Spectroscopic Instrument (DESI), divided into 15 narrow redshift bins, we compute shear ratios that are sensitive to the mean redshift of source galaxies. Using a blinded analysis, we derive constraints on the photo-$z$ bias parameters in source bins 2, 3, and 4, achieving signal-to-noise ratios of 59, 75, and 62, respectively. Our constraints for $\mathrm{\Delta }{z}_2$, $\mathrm{\Delta }{z}_3$, and $\mathrm{\Delta }{z}_4$ are consistent with those from HSC Y3 cosmic shear modeling. We observe a mild shift in the $\mathrm{\Delta }{z}_3\text{−}\mathrm{\Delta }{z}_4$ plane due to the heterogeneous depth of the lens sample, which disappears when using only DESI Data Release 1 lenses. Combining shear-ratio measurements with cosmic shear data, we obtain joint constraints on cosmological parameters: ${\mathrm{\Omega }}_{\mathrm{m}}=0.304_{-0.029}^{+0.03}$ and $S_8=0.773_{-0.031}^{+0.031}$, consistent with cosmic shear-only results. This work demonstrates the utility of small-scale lensing as an independent probe for calibrating photometric redshift bias in weak lensing cosmology.

We analytically study the gauge dependence of scalar–induced gravitational waves (SIGWs) sourced by primordial isocurvature perturbations during radiation domination, working across nine gauges. Through analytical integrations of the kernels supported by graphical comparison we identify a clear dichotomy. We find that in some gauges viz. the uniform-density, total-matter, uniform-curvature, comoving-orthogonal, and transverse-traceless gauges the energy density grows polynomially in conformal time ${\eta }^n$, where $n$ varies from 2 to 8, while in rest of the gauges viz. the longitudinal, uniform-expansion, Newtonian-motion, and N-body gauges the late-time energy spectrum converges, and SIGWs behave as radiation. For subhorizon modes ($k\eta \gg 1$), the divergence becomes severe, showing that SIGWs are gauge-dependent observables in this regime. We resolve it through a kernel projection that isolates the luminal, freely propagating gravitational wave components [oscillating as $\sin (k\eta )$ and $\cos (k\eta )$], eliminating spurious contributions. The resulting kernel decays as $(k\eta {)}^{-1}$ and yields a finite, gauge-independent late-time spectrum, confirming that only luminal modes represent physical SIGWs.

Heavy neutral leptons (HNLs) are well-motivated new physics candidates. The mixing of sub-GeV HNLs with active neutrinos is severely constrained by cosmology. In particular, the success of big bang nucleosynthesis (BBN) requires the HNL lifetime to be shorter than about 0.02 sec if they were in thermal equilibrium, thus excluding a wide range of mixing angles accessible to terrestrial experiments. In order to justify the laboratory searches in this cosmologically forbidden region, it is often argued that adding new dark sector decay modes of HNLs can evade the stringent BBN constraint. Here we rule out this possibility and show that, contrary to the naive expectation, HNLs with significant dark decay modes actually lead to stronger cosmological bounds. This is mainly because of the increase in the extra radiation energy density in the Universe around the BBN epoch, which causes observable effects in the primordial helium fraction and $\mathrm{\Delta }{N}_{\mathrm{eff}}$. Our result has major implications for laboratory searches of HNLs.

Self-interacting dark matter (SIDM) represents a compelling alternative to collisionless dark matter, with diverse phenomenological signals from dwarf galaxy to galaxy cluster scales. We present new constraints on the SIDM cross section from the galaxy cluster MACS J0138-2155, host to the strongly lensed supernovae Requiem and Encore. Our analysis combines strong gravitational lensing with spatially resolved stellar kinematics of the central galaxy, employing several methodological advances over previous cluster-scale SIDM studies. The result is a self-consistent measurement of the density profile of MACS J0138-2155 across two orders of magnitude in radius. Our lensing and kinematics analyses individually yield highly consistent results, and from their combination, we report a 95% confidence upper limit on the SIDM cross section of $\sigma /m<0.613{\mathrm{cm}}^2/\mathrm{g}$, at an interaction velocity of $⟨v_{\mathrm{pair}}⟩<2090\mathrm{km}/\mathrm{s}$. This constraint, derived from the most detailed single-system analysis to date, is competitive with previous cluster-scale limits while demonstrating the power of combining complementary gravitational probes. The methodology developed here advances precision cluster lens modeling and will inform future studies of dark matter physics, as well as time-delay cosmography in this unique strong lensing system. Additionally, our results imply SN Requiem will reappear sooner than previously reported, with a $1\sigma$ CL between January 2027 and November 2028 at ${\mathrm{H}}_0=67.7\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$.

Extreme mass-ratio inspirals pose a difficult challenge in terms of both search and parameter estimation for upcoming space-based gravitational-wave detectors such as LISA. Their signals are long and of complex morphology, meaning they carry a large amount of information about their source, but their waveforms are expensive to compute and they occupy a vast and multimodal parameter space. We explore how sequential simulation-based inference methods, specifically truncated marginal neural ratio estimation, could offer solutions to some of the challenges surrounding extreme-mass-ratio inspiral data analysis. We show that this method can efficiently narrow down the volume of the complex 11-dimensional search parameter space by a factor of ${10}^6–{10}^7$ and provide one-dimensional marginal proposal distributions for nonspinning extreme-mass-ratio inspirals. We discuss the current limitations of this approach and place it in the broader context of a global strategy for future space-based gravitational-wave data analysis.

Ground-based radio telescopes are routinely used to search for light dark matter (DM) candidates such as axionlike particles or dark photons. However, these instruments face inherent limitations to push the searches to masses below ${10}^{-7}\mathrm{eV}$, due to the effect of the Earth’s ionosphere. The extant and planned space- or Moon-based radio telescopes motivate this study: We systematically investigate their sensitivity to resonant conversion of light DM into radio signals from three solar system targets: the Sun, the Earth, and Jupiter. The perspectives are especially encouraging for dark photon searches using the Sun as a target, and for axionlike particles conversion in Jupiter’s magnetosphere.

The Einstein Telescope (ET), a planned third-generation gravitational-wave (GW) observatory, will offer significantly improved sensitivity, introducing new challenges for data analysis and computing. To prepare for these demands, the ET community has initiated a series of mock data challenges (MDCs) aimed at developing and testing analysis pipelines under realistic conditions. This paper presents the first ET MDC, providing an overview of the simulated dataset and the properties of the injected GW signals, with a focus on populations of compact binary coalescences and Gaussian noise. A tutorial is also included to guide users in accessing the data and performing basic analyses. This initial challenge establishes a baseline for future MDCs and supports collaborative efforts toward the successful scientific operation of the ET.

Nearby pulsars within $\sim 1\mathrm{kpc}$ are considered to be possible sources of 10–500 GeV cosmic-ray positron excess measured by PAMELA and AMS-02. A TeV halo around Geminga is detected by High-Altitude Water Cherenkov Observatory, and the measurements of its surface brightness profile indicate a slow particle diffusion surrounding the source. This result challenges the pulsar interpretation of the positron excess. The observations at GeV energies provide direct information on the electron/positron density in the GeV nebula, which can offer more direct constraints on the origin of the positron excess. Two previous works have performed analyses on the GeV emission of the pulsar halo but focused on the energy band above 8 GeV. In this work, we use a longer dataset from the Fermi Large Area Telescope (LAT) to reanalyze the GeV halo emission of Geminga, extending the analysis to cover the energy range of 1–1000 GeV. We find that the analysis in this wider energy range results in a low significance of the halo emission. This can be attributed to the Galactic interstellar emission model being unable to perfectly fit the background over this broader energy range and due to the low measured halo flux at $<10\mathrm{GeV}$ energies leading to a mismatch between the observation and model expectation. We also derive the spectral energy distribution of the tentative halo emission, which shows a very hard spectrum in the 1–10 GeV range.

We present a Monte Carlo study of galactic cosmic-ray energy deposition and its implications for stratospheric chemistry, performed with the geant4 toolkit. Primary nuclei (protons, $\alpha$, CNO, and Si) were propagated through an atmosphere modeled from 0 to $120\mathrm{g}{\mathrm{cm}}^{-2}$, considering both polar ($R_{\mathrm{c}}=0.1\mathrm{GV}$) and equatorial ($R_{\mathrm{c}}=15\mathrm{GV}$) geomagnetic cutoff conditions. The simulations resolve the variation of energy deposition with altitude for primary and secondary particles, revealing that $\sim 96\%$ of the stratospheric energy budget arises from cascade secondaries within the 15–35 km domain. By converting layer-resolved energy deposition into ion pair production rates, we quantify the resulting formation of odd-nitrogen (${\mathrm{NO}}_{\mathrm{x}}$) and odd-hydrogen (${\mathrm{HO}}_{\mathrm{x}}$) radicals, which catalyze the destruction of ozone. The modeled production rates peak between 18 and 22 km altitude, leading to an estimated fractional ozone decrease of the order of ${10}^{-3}-{10}^{-2}$ under average galactic cosmic-ray fluxes, consistent with observed background modulation over the solar cycle. These results establish a physically consistent link between cosmic-ray-induced energy deposition and ozone chemistry, providing a benchmark framework for coupling high-energy particle transport to atmospheric photochemical models.

We study the detectability of GeV-band gamma-ray polarization with the AMS-02 experiment and its proposed successor AMS-100, from Galactic and extragalactic sources. Characterizing gamma-ray polarization in this energy range could shed light on gamma-ray emission mechanisms in the sources; physics beyond the Standard Model, such as the presence of axionlike particles (ALPs), could also induce a distinctive energy-dependent polarization signal due to propagation effects in magnetic fields. We present estimates for the minimum detectable polarization from bright sources and the forecast reach for ALPs. We show that AMS-02 will have sensitivity to gamma-ray polarization only for the brightest steady-state Galactic sources, such as the Vela and Geminga pulsars; it is not expected to be capable of detecting polarization in Galactic or extragalactic sources that have been previously proposed as good targets for ALP searches with gamma-ray intensity measurements. However, AMS-100 observing the extragalactic source NGC1275 would be expected to probe new parameter space even for unfavorable $B$-field models, with prospects to measure the energy-dependence of such a signal. For Galactic sources, polarization measurements could provide a unique test of scenarios where ALPs induce energy-dependent features in the photon intensity. However, in the absence of a bright transient source (such as a Galactic supernova), the parameter space that would be probed by this approach with ten years of AMS-100 data is already nominally excluded by other experiments, although this conflict may be avoided in specific ALP models.

In this work, we study the renormalization-group evolution of parameters in the three-dimensional effective field theory (3D EFT) that describes the thermally driven electroweak phase transition of the Higgs field. We consider tree-level and radiatively generated barriers induced by beyond the Standard Model physics, enabling a first-order phase transition at and below the soft scale, respectively. For each case, we compute the two-loop running of the 3D EFT couplings, including the effects of the leading nonrenormalizable terms. We then analyze how the new contributions to the beta functions compare with those in the super-renormalizable case, highlighting their impact on perturbative computations of the scalar potential, which describes the vacuum structure of the theory. By incorporating higher-order corrections in the mass parameter evolution, as well as the running of other effective operators, we set the stage for testing their impact on phase transition dynamics in lattice simulations.

Motivated by several mild excesses around 95 GeV, we investigate the prospects for a light scalar $S$ produced via Higgsstrahlung, $e^{+}{e}^{-}\to Z({\mu }^{+}{\mu }^{-})S$, at future $e^{+}{e}^{-}$ Higgs factories. We take the CEPC as a benchmark, with a center-of-mass energy of $\sqrt{s}=240\mathrm{GeV}$ and an integrated luminosity of $L=20{\mathrm{ab}}^{-1}$. We focus on the decay modes $S\to {\tau }^{+}{\tau }^{-}$ and $S\to b\overline{b}$. To maximize sensitivity, we employ the particle-level transformer networks particle transformer (ParT) and its more-interactive variant MIParT, which exploit the features of all reconstructed objects and their correlations. For a representative signal benchmark, this approach improves the expected statistical precision on the signal strength by factors of 2.3 in the ${\tau }^{+}{\tau }^{-}$ channel and 1.4 in the $b\overline{b}$ channel compared to a cut-based analysis. Within the flipped next-to-two-Higgs-doublet model (N2HDM-F), the CEPC can measure the signal strength with a statistical precision down to 1.0% in the ${\tau }^{+}{\tau }^{-}$ channel and 0.69% in the $b\overline{b}$ channel using MIParT. It can achieve a $5\sigma$ discovery for ${\mu }_{\tau \tau }^{ZS}>1.6\times {10}^{-2}$ or ${\mu }_{bb}^{ZS}>5.0\times {10}^{-3}$, and reach 1% precision for ${\mu }_{\tau \tau }^{ZS}>0.93$ or ${\mu }_{bb}^{ZS}>0.14$. These gains are expected to qualitatively carry over to other future lepton colliders such as FCC-ee and the ILC. Our results demonstrate the potential of particle-level machine-learning techniques to strengthen light Higgs searches at future $e^{+}{e}^{-}$ Higgs factories.

We introduce a new class of $U(1{)}_X$ symmetries where all Standard Model fermions are “chiral,” i.e., the left- and right-handed components have different charges under the $U(1{)}_X$ symmetry. Gauge anomaly cancellation is achieved by introducing three Standard Model gauge singlet dark fermions ($f^i$; $i=1$, 2, 3) charged under this symmetry. We systematically present chiral solutions for cases in which (a) one, (b) two, or (c) all three generations of Standard Model fermions are charged under the $U(1{)}_X$ symmetry. The $U(1{)}_X$ charges of these dark fermions are uniquely determined by anomaly cancellation conditions. These new fermions belong to the dark sector, with the lightest of them being a good dark matter candidate. Additionally, the $Z^{\prime }$ gauge boson mediates interactions between the dark and visible sectors, and we call this $U(1{)}_X$ symmetry as the “dark hypercharge” symmetry. Using a benchmark model, we explore phenomenological implications in the heavy $Z^{\prime }$ case ($M_{Z^{\prime }}>M_Z$), analyzing collider constraints and examining the lightest dark fermion’s viability as dark matter. Our analysis shows that it satisfies all current dark matter constraints over a wide range of dark matter mass.

We investigate S-wave kaon-nucleon ($KN$) interactions with strangeness $S=+1$ in lattice QCD using the time-dependent HAL QCD method. Employing the ($2+1$)-flavor gauge configuration with $m_{\pi }\approx 137\mathrm{MeV}$ and $m_K\approx 502\mathrm{MeV}$, we calculate the $KN$ potentials at the leading order in the derivative expansion. The potentials in both isospin channels ($I=1$ and $I=0$) exhibit repulsion at short distances, while only the $I=0$ potential has a small attractive pocket at intermediate distances. The phase shifts computed from these potentials show no signals corresponding to resonances or bound states in both isospin channels, suggesting the absence of the ${\mathrm{\Theta }}^{+}(1540)$ pentaquark in the S-wave $KN$ systems. The scattering lengths result in $a_0^{I=1}=-0.226(5){(}_{-0}^{+5})\mathrm{fm}$ and $a_0^{I=0}=+0.028(61){(}_{-26}^{+3})\mathrm{fm}$. Our results of the S-wave cross sections for $I=1$ are consistent with some of the experimental data within $2–3\sigma$, while they deviate from others. The results for $I=0$, combined with recent studies on chiral perturbation theory, suggest that the scattering amplitudes in this channel are dominated by P-wave components rather than S-wave.