We present a measurement of the pairwise kinematic Sunyaev-Zel’dovich (kSZ) signal using the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Sample (BGS) Data Release 1 (DR1) galaxy sample overlapping with the Atacama Cosmology Telescope (ACT) CMB temperature map. Our analysis makes use of 1.6 million galaxies with stellar masses $\log M_{\star }/M_{\odot }>10$, and we explore measurements across a range of aperture sizes (${2.1}^{\prime }<{\theta }_{\mathrm{ap}}<{3.5}^{\prime }$) and stellar mass selections. This statistic directly probes the velocity field of the large-scale structure, a unique observable of cosmic dynamics and modified gravity. In particular, at low redshifts, this quantity is especially interesting, as deviations from General Relativity are expected to be largest. Notably, our result represents the highest-significance low-redshift ($z\sim 0.3$) detection of the kSZ pairwise effect yet. In our most optimal configuration (${\theta }_{\mathrm{ap}}={3.3}^{\prime }$, $\log M_{\star }>11$), we achieve a $5\sigma$ detection. Assuming that an estimate of the optical depth and galaxy bias of the sample exists via e.g., external observables, this measurement constrains the fundamental cosmological combination $H_{0}f{\sigma }_8^2$. A key challenge is the degeneracy with the galaxy optical depth. We address this by combining CMB lensing, which allows us to infer the halo mass and galaxy population properties, with hydrodynamical simulation estimates of the mean optical depth, $\overline{\tau }$. We stress that this is a proof-of-concept analysis; with BGS DR2 data we expect to improve the statistical precision by roughly a factor of two, paving the way toward robust tests of modified gravity with kSZ-informed velocity-field measurements at low redshift.

We investigate the observational tests of generalized mass-to-horizon entropic cosmology by incorporating large-scale structure growth data in addition to purely geometric probes. The theoretical framework is constructed from a generalized mass-to-horizon scaling relation, $M\propto L^n$, which implies a corresponding generalized entropic functional $S_n\propto L^{n+1}$. Within this setting, cosmic acceleration arises as an emergent phenomenon driven by an entropic force acting on the cosmological horizon. While earlier studies demonstrated that these entropic cosmologies can reproduce the background expansion history of the standard Lambda cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) model, here we present a comprehensive observational analysis that jointly employs $\mathrm{Pantheon}+\text{Type}$ Ia supernova data with SH0ES Calibration, DESI DR2 baryon acoustic oscillation measurements, cosmic microwave background distance priors, and a suite of cosmological structure growth observations. A Bayesian model comparison indicates that the entropic models are statistically preferred over the conventional $\mathrm{\Lambda }\mathrm{CDM}$ scenario, thereby providing strong support for an entropic origin of the observed late-time cosmic acceleration in place of a fundamental cosmological constant.

Skew spectra allow us to extract non-Gaussian information by taking the square of a map and finding the power spectrum of this new map with the original map. This allows us to use much of the infrastructure of power spectra and avoid the intricacies of estimating three point statistics. In this paper we present the first extension of skew spectra to arbitrary spin-$s$ fields, as a means to extract non-Gaussian information efficiently from cosmological datasets like cosmic shear or cosmic microwave background polarization. We apply the formalism to weak lensing in the context of large scale structure, and discuss different ways of combining fields to build skew spectra, all while avoiding the problems associated with mass mapping. We provide plots of these new statistics for $\mathrm{\Lambda }$ cold dark matter and vary cosmological parameters.

We investigate the luminosity-temperature ($L\text{−}T$) relation of galaxy clusters as a probe for testing modified gravity (MG) theories, focusing on $f(R)$ gravity and symmetron models. Using an improved semianalytic framework that incorporates angular momentum acquisition, dynamical friction, and shock heating within the modified punctuated equilibrium model, we compare predictions against hydrodynamical simulations and observational data. While massive clusters remain largely screened and follow standard $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) predictions, low-mass systems ($kT\lesssim 1–2\mathrm{keV}$) exhibit systematic deviations characterized by steeper $L\text{−}T$ slopes in MG scenarios. Crucially, we demonstrate that these signatures cannot be mimicked by conventional astrophysical processes such as feedback or angular momentum effects, which primarily affect normalization rather than curvature. Our results establish the $L-T$ relation as a robust diagnostic tool for distinguishing general relativity from screened MG theories, with the strongest discriminatory power emerging at group scales accessible to current and future x-ray surveys. Moreover, a normalized reduced ${\chi }^2$ analysis of the $L\text{−}T$ relation shows that MG models provide significantly better agreement with observational data than $\mathrm{\Lambda }\mathrm{CDM}$, with several realizations achieving excellent fits while the $\mathrm{\Lambda }\mathrm{CDM}$ model consistently performs worst.

The abundance and mass function of primordial black holes (PBHs) are often estimated using the Press–Schechter (PS) formalism. In the case of halo formation, the PS formalism suffers from the miscounting of regions collapsing into halos, known as the cloud-in-cloud problem, which is usually corrected by introducing a multiplicative “fudge factor 2.” By analogy, this factor has sometimes been applied to PBH calculations, although its validity has remained unsettled. We reformulate the PS approach for PBHs (forming during radiation-dominated epoch) within the excursion set framework, where the smoothed density contrast undergoes a stochastic random walk as the smoothing scale varies and collapse is identified with the first threshold crossing. While the halo case is described by a Markovian process, we show that the PBH case is non-Markovian, even when the sharp-k filter Window function is adopted. Decomposing the total collapse probability into two distinct components of the stochastic motion, we numerically confirm that their contributions are exactly equal in the case of halo formation, justifying the fudge factor. For PBHs, however, we demonstrate that this equality no longer holds, and consistent inclusion of both contributions is essential to ensure a positive-definite mass function. Our results clarify the origin of the ambiguity surrounding the fudge factor and establish a robust theoretical foundation for PBH abundance calculations.

The persistent discrepancy between the experimental measurement and the Standard Model (SM) prediction of the muon’s anomalous magnetic moment $(g-2{)}_{\mu }$ remains one of the most intriguing hints of physics beyond the SM. A well-motivated explanation involves a light $Z^{\prime }$ gauge boson associated with a broken $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry. Such a boson not only resolves the $(g-2{)}_{\mu }$ anomaly, but also induces resonant interactions between high-energy cosmic neutrinos and the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$), potentially shaping the observable neutrino flux at Earth. In this work, we explore the implications of such interactions for the cosmic propagation of high-energy neutrinos. We compute the optical depth for neutrino attenuation via $Z^{\prime }$-mediated scattering, accounting for neutrino masses, hierarchies, and thermal distributions. We delineate the regions in $(m_{Z^{\prime }},m_{\nu })$ space where the optical depth exceeds unity, defining a “neutrino cosmic horizon” beyond which high-energy neutrinos are significantly attenuated. We confront these results with the parameter space required to simultaneously explain the muon $g-2$ anomaly and ease the Hubble tension via an additional contribution to the effective number of relativistic degrees of freedom, $\mathrm{\Delta }{N}_{\mathrm{eff}}\simeq 0.2–0.5$. Our analysis reveals a consistent region in parameter space where all three phenomena [$(g-2{)}_{\mu }$, $N_{\mathrm{eff}}$, and high-energy neutrino attenuation] can be explained by the same light mediator. These findings motivate future searches for spectral features in IceCube and its next-generation successors as indirect probes of new physics in the neutrino sector.

It is shown that conformal symmetry exists in force-free electrodynamics (FFE) in Minkowski spacetime, a foundational framework for describing magnetospheres around astronomical objects. In force-free magnetospheres, charges are constrained to move along magnetic field lines and experience zero Lorentz force, due to the everywhere perpendicular orientation of electric and magnetic fields. However, a general angle-preserving conformal mapping of force-free fields does not necessarily produce another physically admissible force-free configuration when sources are present. In this work, we demonstrate that such invariance can nevertheless arise for certain choices of the free functions. Specifically, the governing stream equation is shown to be invariant under Möbius transformations. This symmetry reveals a structural linkage between known solutions and, notably, maps the region inside a magnetospheric horizon (the light surface) of one solution to the exterior of its dual counterpart, and vice versa.

Recent work has highlighted the importance of a fully relativistic treatment of the dephasing of gravitational waves induced by dark-matter overdensities in extreme mass-ratio inspirals (EMRIs). However, a general-relativistic description of the dark matter phase-space distribution is currently available only for the case of a dark matter “spike” arising from adiabatic black hole growth. Here we develop a fully general-relativistic formalism for the more realistic scenario in which a supermassive stellar progenitor collapses to a black hole and produces a shallower dark matter overdensity, or “mound.” We follow self-consistently the evolution of the supermassive star, its collapse, and the subsequent growth of the resulting black hole, together with the collisionless dark matter orbits. We find that in the regime where the collapse becomes nonadiabatic, the dark matter distribution function is significantly reshaped, with a clear depletion in the low-binding-energy region of phase space. Our results provide a more realistic prediction for the dark matter phase-space distribution around supermassive black holes, which is an essential step in using future EMRI observations to extract information about their formation history and the nature of dark matter.

The capability of the ALICE@LHC and STAR@RHIC experiments to reconstruct $D$ mesons has enabled femtoscopic correlation measurements of open-charm mesons in both small and large systems. In this work, we present a theoretical calculation of the correlation functions of $D$ and $\overline{D}$ mesons with nucleons, based on the Koonin-Pratt formalism. We employ an effective Lagrangian to model the interaction between charmed mesons and baryons and apply the TROY formalism to obtain the off-shell $T$-matrix in coupled channels, incorporating the effect of the Coulomb interaction when the pair involves two charged particles. The resulting full coupled-channel wave function is inserted into the Koonin-Pratt equation with channel weights derived from a thermal model. Additionally, we compute the correlation functions using the Lednický-Lyuboshitz approximation with low-energy scattering parameters extracted from the unitarized amplitudes. We compare these two approaches and provide predictions for different correlated pairs. Our results can be tested against current and future experimental data from the ALICE and STAR Collaborations in both proton-proton and heavy-ion collisions.

The thermal photon emission rate $\frac{d\mathrm{\Gamma }}{dk}$ and dc electric conductivity ${\sigma }_Q$ of the strongly coupled quark-gluon plasma are investigated around the critical end point in a $N_f=2+1$ holographic QCD model with parameters obtained from machine learning. It is found that both thermal photon emission rate and electric conductivity grow most obviously around $T_c$, which agrees with the previous studies, and the result of electric conductivity at zero chemical potential resembles the lattice results. Moreover, it is found that both the temperature derivative of the electric conductivity and thermal photon emission rate diverge at the critical end point.

We perform an improved perturbative QCD study of the decays $B_c^{+}\to {\eta }_c{L}^{+}$, where $L$ denotes the light ground-state pseudoscalar, vector mesons and the corresponding $p$-wave scalar, axial-vector, and tensor ones, and predict their branching ratios (BRs) associated with relative ratios at leading order in the strong coupling ${\alpha }_s$. Our results $\mathrm{BR}(B_c^{+}\to {\eta }_c{\pi }^{+})=(2.03_{-0.41}^{+0.53})\times {10}^{-3}$ and $\mathrm{BR}(B_c^{+}\to {\eta }_c{\pi }^{+})/\mathrm{BR}(B_c^{+}\to J/\psi {\pi }^{+})=1.74_{-0.50}^{+0.66}$ are consistent with several available predictions in different approaches within uncertainties. Inputting the measured ${\eta }_c\to p\overline{p}$ and ${\eta }_c\to {\pi }^{+}{\pi }^{-}({\pi }^{+}{\pi }^{-},K^{+}{K}^{-},p\overline{p})$ BRs with $p$ here being a proton, we derive the multibody $B_c^{+}\to {\eta }_c(\pi ,\rho {)}^{+}$ BRs through secondary decay chains via resonance ${\eta }_c$ under the narrow-width approximation, which might facilitate the (near-)future tests of $B_c\to {\eta }_c$ decays. Under the $q\overline{q}$ assignment for light scalars, different to $B_c$ decaying into $J/\psi$ plus a scalar meson and other $B_c^{+}\to {\eta }_c{L}^{+}$ modes, surprisingly small $\mathrm{\Delta }S=0$ BRs around $\mathcal{O}({10}^{-7}-{10}^{-9})$ and highly large ratios near $\mathcal{O}({10}^2)$ between the $\mathrm{\Delta }S=1$ and $\mathrm{\Delta }S=0$ BRs are found in the $B_c$ decays to ${\eta }_c$ plus light scalars, with $S$ being strange number. Many large BRs and interesting ratios presented in this work could be tested by the Large Hadron Collider experiments, which would help us to examine the reliability of this improved perturbative QCD formalism for $B_c$-meson decays and further understand the QCD dynamics in the considered decay modes as well as in the related hadrons.

We investigate how matter density distributions affect thin-wall bubble formation in the asymmetron mechanism, a scalar–tensor theory with a universal coupling to matter and explicit symmetry breaking, and analyze the stability of its metastable state. We show that the screening mechanism of the asymmetron inside dense objects induces a surface tension associated with the boundary of the screening object, leading to a richer class of bubble solutions than the standard Coleman-Callan bulk nucleation. These boundary surface tensions are used to modify the Nambu-Goto action for instantons, allowing for the computation of the corresponding Euclidean action for bubbles nucleating on flat planes, as well as on concave and convex cylindrical surfaces. We find that the smallest Euclidean action occurs for bubbles nucleating along the edge of a concave spherical surface. Comparing this edge nucleation channel with the bulk one, we determine the maximum curvature radius for which concave edge nucleation is preferred. Since the maximum radius of curvature is exponentially suppressed by the action of a bulk bubble, we find that within the regime of the instanton approximation, edge nucleation is always preferred. This is largely due to the weak couplings of the asymmetron. We apply these findings to determine the maximum curvature radius of a cosmic void and discuss how our results affect the seeding of $N$-body simulations of asymmetron domains, showing that domain wall nucleation preferentially occurs at the edges of cosmological voids. We also demonstrate that the presence of a homogeneous gas around the dense substrates reduces the maximum curvature radius, enabling bulk bubbles to form preferentially as the asymmetron undergoes a density-driven phase transition.

Sphaleron dynamics in the Standard Model at high-energy particle collisions remains experimentally unobserved, with theoretical predictions hindered by its nonperturbative real-time nature. In this work, we investigate a quantum simulation approach to this challenge. Taking the $1+1\mathrm{D}O(3)$ nonlinear $\sigma$-model as a protocol towards studying dynamics of the sphaleron in electroweak theory, we identify the sphaleron configuration and establish lattice parameters that reproduce continuum sphaleron energies with controlled precision. We then develop quantum algorithms to simulate sphaleron evolutions where quantum effects can be included. This work lays the ground to establish quantum simulations for studying the interaction between classical topological objects and particles in the quantum field theory that are usually inaccessible to classical methods and computations.

We propose the first scotogenic neutrino mass model with gauged lepton number $U(1{)}_L$, which is spontaneously broken by three units $\mathrm{\Delta }L=3$ down to a residual discrete gauge symmetry ${\mathbb{Z}}_6$. The latter guarantees that neutrinos acquire tiny Dirac masses via a one-loop scotogenic mechanism, simultaneously stabilizing the lightest electrically neutral particle with nontrivial charge under the preserved ${\mathbb{Z}}_6$ symmetry. In our model there is a scalar particle identified as weakly interacting massive particle dark matter (DM) candidate. We analyzed its compatibility with the existing data on direct DM detection experiments and the DM relic abundance. We also address charged lepton flavor violating decays in our model and find that their predicted rates are within the reach of current experimental sensitivity.

We investigate lepton number violation (LNV) induced by $\mathrm{\Delta }L=2$ dimension-seven Standard Model effective field theory (SMEFT) operators in the context of same-sign muon colliders. Specifically, we study ${\mu }^{+}{\mu }^{+}\to W^{+}{W}^{+}/W^{+}q{q}^{\prime }$ production at the $\mu \mathrm{TRISTAN}$ at $\sqrt{s}=2\mathrm{TeV}$ with an integrated luminosity of $1{\mathrm{ab}}^{-1}$, using the final-state signature comprising two fat jets. This process is sensitive to eight distinct SMEFT operators, providing a unique avenue for testing LNV beyond the Standard Model. We determine the maximal sensitivity to these operators and compare our results with existing LHC constraints and future projections from the future circular collider. Our findings highlight the potential of same sign muon colliders to serve as powerful probes of LNV and new physics (NP) at the TeV scale.

We propose a predictive $SO(10)$ grand unified theory (GUT) framework for cosmic inflation within the Palatini ${\mathcal{R}}^2$ formulation of gravity. In this model, a GUT Higgs field simultaneously drives inflation and induces intermediate-scale symmetry breaking, thereby linking primordial cosmology, gauge unification, and formation of topological defects. A subsequent partial inflationary phase of $N_I\sim 10–17$ $e$-folds occurring after monopole formation can dilute magnetic monopoles to abundances $Y_M\sim {10}^{-35}–{10}^{-27}$. The model predicts cosmic microwave background (CMB) observables in the range $0.955\lesssim n_s\lesssim 0.974$, accommodating the mild tension between the Planck–BICEP ($n_s\simeq 0.965$) and Planck$+\mathrm{ACT}$ ($n_s\simeq 0.971$) measurements via the $\varphi <M$ and $\varphi >M$ branches, respectively, where $M$ denotes the renormalization scale entering the Coleman–Weinberg potential. The predicted tensor-to-scalar ratio, $r\lesssim 8\times {10}^{-4}$, is consistent with current observational bounds and may be accessible to forthcoming experiments, including the Simons Observatory and LiteBIRD. Furthermore, correlations among the unification scale $M_U$, the inflationary observables $(n_s,r)$, and proton-decay lifetimes reveal a strong complementarity between CMB measurements and proton-decay searches, with regions of parameter space testable by upcoming experiments, such as Hyper-Kamiokande and DUNE.

We investigate long-range, purely leptophilic axial-vector interactions mediated by a light gauge boson $A^{\prime }$ that couples to charged leptons and, by weak symmetry, to left-handed neutrinos. We analyze two realizations, a minimal effective model with muon-only couplings and an anomaly-free axial $U(1{)}^{\prime }$ with intergeneration cancelations. In both cases, the solar neutrino flux acts as an extended current that sources a macroscopic $A^{\prime }$ field at Earth, with spatial components aligned along the Sun-Earth direction. This field produces a distinctive signature in storage-ring measurements of the muon anomalous magnetic moment, $(g-2{)}_{\mu }$, namely a diurnal, sign-changing contribution that is positive during daytime and negative at night, superimposed on a time-independent positive offset. We obtain bounds $g^{\prime }\lesssim \mathcal{O}({10}^{-19})$ in both model frameworks for a light, effectively massless mediator. For completeness, we map the solar-neutrino–sourced potential to electron spin-sensor experiments and find $g^{\prime }\lesssim \mathcal{O}({10}^{-22})$ in the electron channel.

Dark matter (DM) and the baryon asymmetry of the Universe (BAU) are among the most compelling indications of physics beyond the Standard Model. We revisit the inelastic Higgs-portal complex singlet, a minimal framework in which a complex scalar splits into two nearly degenerate real states, with an off-diagonal Higgs-portal interaction that drives coannihilation to set the relic density, while the elastic DM-Higgs coupling can be tuned small enough to evade direct-detection limits. This setup naturally supports a strong first-order electroweak phase transition (SFOEWPT) and can account for the longstanding Galactic Center gamma-ray excess (GCE) via present-day DM annihilation into Higgs pairs. In this work, we show that the same framework, extended by a $Z_2$-symmetric dimension-6 $CP$-violating top Yukawa operator, can also generate the BAU via the electroweak baryogenesis (EWBG) mechanism. The cosmological history involves a two-step electroweak phase transition: first, the singlet fields acquire nonzero vacuum expectation values ($vevs$); then a strongly first-order transition occurs in which the Higgs develops its nonzero $vev$ while the singlet $vevs$ vanish. During this second step, both fields remain nonzero only within the advancing bubble wall, generating wall-localized $CP$ violation that biases sphaleron transitions and enables EWBG. After the phase transition, $CP$ and $Z_2$ symmetries are restored: the lightest singlet state becomes a stable DM candidate, while the vanishing singlet $vevs$ allow the model to naturally satisfy the stringent constraints on $CP$ violation. We delineate the SFOEWPT-favored parameter space, identifying the criteria for the two-step phase transition region that simultaneously yields the observed BAU and relic density, explains the GCE, and predicts gravitational wave spectra accessible to next-generation space-based detectors.

Supernovae offer a unique hot and dense environment to probe new physics beyond the Standard Model. We investigate supernova cooling constraints on lepton-flavor-violating (LFV) axions and axionlike particles (ALPs) that couple to electrons and muons. For LFV-ALP production in supernovae, muon decay and lepton bremsstrahlung have been considered previously. In this work, we identify the electron-muon coalescence channel as an efficient new production mechanism in the high-mass regime. We also include the semi-Compton scattering process, which has recently been shown to provide sizable contributions for electron-coupled ALPs. We find that muon decay dominates in the low-mass regime, electron-muon coalescence becomes the leading channel at high masses, and semi-Compton scattering provides the dominant contribution in the intermediate mass range. We find that the electron-muon coalescence process yields the strongest constraints in the mass range of $\sim (115,280)\mathrm{MeV}$, probing the ALP-electron-muon coupling down to $\sim 4\times {10}^{-10}$ for an ALP mass of $\sim 200\mathrm{MeV}$.

Axion dark matter or any ultralight bosonic dark matter can go through Bose-Einstein condensation due to the large phase density, leading to the formation of axion stars or solitons in dark matter halo centers. The formation rate is enhanced in the presence of the substructures expected in the postinflationary scenario for the QCD axion or axionlike particles. An axion star will continue to grow until a critical mass is reached, after which it collapses and then explodes, with the emission of relativistic axions, in a process called an “axinovae.” There can also be accompanying photon emission due to the stimulated decay of axions in the coherent compact axion star. In axion models with a modest enhancement ($\kappa \sim \mathcal{O}(10)$) of the axion-photon coupling $g_{a\gamma }=\kappa \alpha /(2\pi f_a)$ axinovae will contain a significant flux of radio photons. We determine the range of parameters over which axinovae can be detectable with radio transient searches.