We investigate the differences between several proposed formation scenarios for black hole binaries, including isolated stellar evolution, dynamical assembly in dense clusters and active galactic nuclei (AGN) disks, and primordial black holes. Our approach exploits the predicted spin features of each formation channel, and adopts parametrized models of the predicted correlations between the spin magnitudes (and orientations) and mass, inspired by first principles. Using hierarchical Bayesian inference on the recent GWTC-4.0 dataset, we compare these features across all models and assess how well each scenario explains the data. We find that the data strongly favor the presence of a positive correlation between mass and spin magnitude, in agreement with previous studies. Furthermore, the hierarchical scenario provides a better fit to the observations, due to the inclusion of second-generation mergers leading to higher spins at larger masses. The current dataset is not informative enough about spin orientation: the cluster (random orientations) and AGN (aligned orientations) scenarios have comparable Bayesian evidence. Finally, the mass-spin correlation predicted by the primordial scenario gives a poor fit to the data, and this scenario can only account for a subset of the observed events.

In pulsar timing array (PTA) data analysis, noise is typically assumed to be Gaussian, and the marginalized likelihood has a well-established analytical form derived within the framework of Gaussian processes. However, this Gaussianity assumption may break down for certain classes of astrophysical and cosmological signals, particularly for a gravitational wave background (GWB) generated by a population of supermassive black hole binaries (SMBHBs). In this work, we present a new method for testing the presence of non-Gaussian features in PTA data. We go beyond the Gaussian assumption by modeling the noise or signal statistics using a Gaussian mixture model (GMM). An advantage of this approach is that the marginalization of the likelihood remains fully analytical, expressed as a linear combination of Gaussian PTA likelihoods. This makes the method straightforward to implement within existing data analysis tools. Moreover, this method extends beyond the free spectrum analysis by producing posterior probability distributions of higher-order moments inferred from the data, which can be incorporated into spectral refitting techniques. We validate the model using simulations and demonstrate the sensitivity of PTAs to non-Gaussianity by computing the Bayes factor in favor of the GMM as a function of the injected excess moments. We apply the method to a more astrophysically motivated scenario where a single SMBHB is resolved on top of a Gaussian GWB and show that significant non-Gaussianities are introduced by the individual source. Finally, we test our model on a realistic GWB generated from a simulated population of SMBHBs.

Despite the growing number of high-energy neutrinos (TeV–PeV) detected by IceCube, their astrophysical origins remain largely unidentified. Recent observations have linked a few tidal disruption events (TDEs) to the production of high-energy neutrino emission, all of which display dust-reprocessed infrared flares, indicating a dust- and gas-rich environment. By cross-matching the neutrino events and a sample of mid-infrared outbursts in nearby galaxies with transient radio flares, we uncover an optically obscured TDE candidate, SDSS $\mathrm{J}151345.75+311125.2$, which shows both spatial and temporal coincidence with the sub-PeV neutrino event IC170514B. Using a standard equipartition analysis of the synchrotron spectral evolution spanning 605 days post mid-infrared discovery, we find a little evolution in the radio-emitting region, with a kinetic energy up to ${10}^{51}\mathrm{erg}$, depending on the outflow geometry and shock acceleration efficiency assumed. High-resolution European VLBI Network imaging reveals a compact radio emission that is unresolved at a scale of $<2.1\mathrm{pc}$, with a brightness temperature of $T_b>5\times {10}^6\mathrm{K}$, suggesting that the observed late-time radio emission might originate from the interaction between a decelerating outflow and a dense circumnuclear medium. If the association is genuine, the neutrino production is possibly related to the acceleration of protons through $pp$ collisions during the outflow expanding process, implying that the outflow-cloud interaction could provide a physical site with a high-density environment for producing the sub-PeV neutrinos. Such a scenario can be tested with future identifications of radio transients coincident with high-energy neutrinos.

Interpreting multimessenger signals from neutron stars and black holes requires reliable general relativistic magnetohydrodynamics (GRMHD) simulations across rapidly evolving high-performance computing platforms, yet key algorithms are routinely rewritten within infrastructure-specific numerical relativity codes, hindering verification and reuse. We present the General Relativistic Hydrodynamics Library (grhayl), a modular, infrastructure-agnostic GR(M)HD library providing conservative-to-primitive recovery, reconstruction, flux/source and induction operators, equations of state, and neutrino leakage through an intuitive interface. grhayl refactors and extends the mature illinoisgrmhd code into reusable point- and stencilwise kernels, enabling rapid development and cross-code validation in diverse frameworks, while easing adoption of new microphysics and future accelerators. We implement the same kernels in the einstein toolkit (carpet and carpetx) and blackholes@home, demonstrating portability with minimal duplication. Validation combines continuous-integration unit tests with cross-infrastructure comparisons of analytic GRMHD Riemann problems, dynamical Tolman-Oppenheimer-Volkoff evolutions, and binary neutron star mergers, showing comparable or improved behavior over legacy illinoisgrmhd and established einstein toolkit codes.

This study introduces a complete joint angular distribution analysis for the process $e^{+}{e}^{-}\to J/\psi \to B(\to B_1\pi )\overline{B}(\to {\overline{B}}_1\pi )$ with polarized beams, where $B$ and $B_1$ are hyperons. We consider both transverse and longitudinal beam polarization and analyze $CP$ violation in the production and decay of hyperons. We present the complete Fisher information matrix for the sensitivities of the weak decay parameters ${\alpha }_{-},{\alpha }_{+},{\varphi }_{\mathrm{\Xi }}$, and ${\overline{\varphi }}_{\mathrm{\Xi }}$, the $P$-violating term $F_A$, and the EDM $d_B$ (derived from the $CP$-violating term $H_T$), under the BESIII and STCF statistics. We find that polarization enhances the sensitivity of the parameters. Specifically, longitudinal polarization provides a more significant improvement compared to transverse polarization, with the enhancement being more pronounced for single-step decays than for multistep decays. With the expected statistics from the BESIII experiment, the estimated EDM sensitivities for $\mathrm{\Lambda }$ and ${\mathrm{\Sigma }}^{+}$ are on the order of ${10}^{-19}e\mathrm{c}\mathrm{m}$, while those for ${\mathrm{\Xi }}^{-}$ and ${\mathrm{\Xi }}^0$ are ${10}^{-18}e\mathrm{c}\mathrm{m}$. The upcoming STCF experiment is expected to improve these estimates by 1–2 orders of magnitude. Furthermore, $CP$ violation in hyperon decays originates from weak-phase differences among partial-wave amplitudes. Based on a refined isospin analysis, we emphasize the non-negligible contribution of $\mathrm{\Delta }I=3/2$ amplitudes to $CP$ violation and advocate for increased theoretical attention to this aspect in future studies.

We consider the implications of asymptotic safety on two U(1) gauge extensions of the standard model that are minimal in the sense that anomaly cancellation only requires the presence of right-handed neutrinos. We study the UV fixed points of the gauge couplings taking into account kinetic mixing between hypercharge and the new U(1) gauge field. We consider the possibility that the top-bottom mass splitting originates from the effect of differing gauge charges on the nontrivial fixed-point values of their respective Yukawa couplings and assess the impact of the extended gauge symmetry on the viability of this picture.

The upcoming electron-positron collider provides an ideal place to probe deviation from the Standard Model predictions with its clean environment, beam polarization, and significant luminosity. We studied anomalous quartic gauge boson couplings ($VV{W}^{-}{W}^{+},V\in \{\gamma ,Z\}$), triple gauge couplings ($W^{-}{W}^{+}\gamma /Z$), and Higgs-gauge couplings $(HVV,V\in \{W^{\pm },Z,\gamma \})$ induced by $SU(2{)}_L\times U(1{)}_Y$ gauge-invariant dimension-6 operators in $2j{e}^{-}{e}^{+}\mu \cancel{E}$ final events with initial beam polarization. The phase space of two prominent amplitudes—i.e., triple gauge boson production ($WWZ$) and vector boson scattering subprocesses—are selected with kinematic cuts on $m_{e^{-}{e}^{+}}$. The full quantum states of the diboson system in vector boson scattering (VBS) and the triboson system in $WWZ$ are given by 80 and 728 independent parameters (polarizations and spin correlations), respectively, which are obtained in the form of angular asymmetries. Further, the reconstruction of vector polarization asymmetries associated with the $W$ boson and their correlations requires flavor tagging of light jets and is thus neglected. We provide one-parameter limits at a 95% confidence level, combining cross section and spin-related observables. The projected one-parameter constraints on Wilson coefficients (WCs) are found to be more stringent than the current limits reported by the LHC experiments. A channel study highlights that $WWZ$ puts stringent bounds on two $CP$-even WCs, viz. $c_W$ and $c_{WWW}$, while VBS topology puts stringent bounds on the remaining seven WCs. Finally, marginalized limits on all nine anomalous couplings are obtained with Markov chain Monte Carlo analysis. The limits are found to be insensitive to systematic errors and dominated by statistics.

A fermion can be chiral or vectorlike with respect to a given symmetry, depending on its coupling to the corresponding gauge boson. Vectorlike fermions have a distinct property that their left- and right-handed components behave in the same way under the gauge symmetry. In this paper, we investigate an extension of the standard model with an $SU(2)$ doublet of vectorlike leptons and two complex scalars. The new physics effects on the lepton anomalous magnetic moment, as well as the electron and muon pair production processes at $e^{+}{e}^{-}$ colliders are analyzed. Taking into account the updated measurement results of the electron and muon $g-2$, as well as the Large Electron-Positron Collider and the LHC data, the viable parameter space of the model is identified. We also examine the prospect of testing the model using ${\mu }^{+}{\mu }^{-}$ signals from electron-position annihilation at the Future Circular Collider (FCC-ee). The analysis shows that the FCC-ee will be able to exclude a significant part of the parameter space, pinpointing exiguous viable regions to be tested in the future due to its high precision.

We study how out-of-equilibrium effects modify the steady-state propagation of bubble walls during a cosmological first-order electroweak phase transition. Going beyond the local thermal equilibrium approximation, we numerically solve the coupled system of scalar field, hydrodynamic, and Boltzmann equations using a spectral algorithm that allows a first-principle treatment of the collision integral. This approach enables a quantitative assessment of nonequilibrium perturbations in the plasma and their backreaction on the wall motion. Focusing on the singlet extension of the Standard Model as a minimal benchmark scenario, we find that out-of-equilibrium corrections substantially enhance the effective friction on the expanding front, leading to slower wall velocities and broader wall profiles compared to the equilibrium case. These modifications have significant implications for cosmological observables. For instance, they enhance the efficiency of electroweak baryogenesis, thus improving the viability of baryon asymmetry generation within realistic parameter regions that can also be probed by future gravitational wave interferometers.

We present charmonium spectral functions extracted from Euclidean-time correlation functions using sparse modeling (SpM). SpM solves inverse problems by considering only the sparsity of the target solution. To assess the applicability of the method, we first test it with mock data designed to mimic charmonium correlation functions. We demonstrate that while resonance peaks in the spectral functions can be reconstructed using this method, transport peaks are difficult to resolve without introducing further assumptions beyond sparsity. We then apply the method to charmonium correlation functions obtained from lattice quantum chromodynamics (QCD) at temperatures below and above the critical temperature. The results are found to be qualitatively consistent with those obtained using the maximum entropy method, although the transport peak is not clearly resolved. This indicates that, even when relying solely on the assumption of sparsity, the method can capture some relevant features of the underlying physics.

We present a detailed account of the theoretical progress and the computational strategy that led to the nonperturbative determination of the QCD equation of state at temperatures up to the electroweak scale reported in Phys. Rev. Lett. 134, 201904 (2025). The two key ingredients that make such a calculation feasible with controlled uncertainties are (i) the definition of lines of constant physics through the running of a nonperturbatively defined finite-volume coupling across a wide range of energy scales, and (ii) the use of shifted boundary conditions which allow a direct determination of the entropy density thus without the need for a zero-temperature subtraction. Considering the case of QCD with $N_f=3$ massless flavors in the temperature interval between 3 and 165 GeV, we describe the numerical strategy based on integrating in the bare coupling and quark mass, the perturbative improvement of lattice observables, the optimization of numerical simulations, and the continuum extrapolation. Extensive consistency checks, including finite volume and topology freezing effects, confirm the robustness of the method. The final results have a relative accuracy of about 1% or better, and the errors are dominated by the statistical fluctuations of the Monte Carlo ensembles. We also compare our nonperturbative results with predictions from standard and hard thermal loop perturbation theory showing that at the level of %-precision contributions beyond those known, including nonperturbative ones due to ultrasoft modes, are relevant up to the highest temperatures explored. The methodological framework is general and readily applicable to QCD with four and five massive quark flavors and to other thermal observables, paving the way for systematic nonperturbative studies of thermal QCD at very high temperatures.

We revisit the two-dimensional Fourier transform of generalized parton distributions (GPDs) at nonzero skewness. At $\eta =0$ it reduces to the standard impact-parameter density, while at $\eta \ne 0$ it is an off-forward amplitude that we interpret as a genuine parton–nucleon correlation. Its overall strength (the transverse-plane integral of the density) is fixed by the GPD at the kinematic point $t=-c_{\eta }=-4{\eta }^2{m}_N^2/(1-{\eta }^2)$ and decreases monotonically with the rapidity gap $\mathrm{\Delta }y=\ln [(1+\eta )/(1-\eta )]=2\mathrm{artanh}(\eta )$. This rapidity dependence implies rapidity-modified Ji identities that connect helicity, orbital, and total angular momenta of the correlation in closed form. To quantify these effects, we construct leading-twist quark and gluon GPDs in a string-based conformal framework: conformal moments are parametrized by linear open- and closed-string Regge trajectories with slopes constrained by parton distribution functions (PDFs), hadron/glueball spectroscopy, and form-factor data, and GPDs are reconstructed over the full $(x,\eta ,t)$ domain by Mellin-Barnes inversion with next-to-leading order evolution. We find qualitative agreement (and fair quantitative agreement within quoted uncertainties) for several moments and selected nonsinglet $x$-space channels at $\mu =2\mathrm{GeV}$ when compared with lattice QCD, while we also identify channels with visible tension and discuss likely sources (PDF priors and $t$-slope systematics).

We investigate the thermodynamic properties of cold magnetized quark matter within a nonlocal Nambu–Jona-Lasinio model. Our study addresses the equation of state, anisotropic pressures, quark density, speed of sound, and magnetic susceptibility, with direct comparison to the chiral limit. Strong magnetic fields are found to generate marked anisotropy; the longitudinal pressure and speed of sound are enhanced, approaching the causal bound in the lowest Landau-level regime, while the transverse components are systematically reduced. The quark density exhibits magnetic catalysis, increasing with both the chemical potential and the magnetic field strength. At moderate to high fields, the critical chemical potential decreases with increasing $eB$, signaling the occurrence of inverse magnetic catalysis at finite chemical potential. Magnetic susceptibility displays oscillations around zero in low fields, driven by de Haas–van Alphen-like effects, and settles at positive values for strong fields, consistent with an overall growth of magnetization. Compared with the chiral limit, the inclusion of finite current quark masses does not modify the overall oscillatory behavior, but changes the nature of the Landau-level transitions, which become weakly first order instead of second order.

We propose a hybrid equation of state ($\mathrm{VDF}+\mathrm{MIT}$ EoS) to describe the hadron-quark phase transition in dense nuclear matter. By coupling this EoS with the a multiphase transport-hadron cascade transport model and comparing to recent experimental data on proton and $\mathrm{\Lambda }$ directed flow $v_1$, we constrain the transition to likely occur near $5{\rho }_0–6{\rho }_0$, ruling out transitions below $3{\rho }_0$. Furthermore, we introduce the energy derivative of the midrapidity $v_1$ slope, $d(d{v}_1/dy)/d(\sqrt{s_{NN}})$, as a weakly model-dependent observable. Its zero crossing provides a direct signature of the phase transition critical point, offering a new tool for mapping the quantum chromodynamics phase diagram in future experiments.

The gallium anomaly, a persistent discrepancy exceeding $4\sigma$ in the ${}^{71}\mathrm{Ga}$ neutrino capture rates from ${}^{51}\mathrm{Cr}$ and ${}^{37}\mathrm{Ar}$ radioactive sources by the GALLEX, SAGE, and recently BEST experiments, has challenged particle physics and nuclear theory for over three decades. We present a new calculation of the neutrino capture cross section, abandoning the conventional leading-order approximation for electronic wave functions by numerically solving the Dirac-Coulomb equation for both bound and continuum electron states. Finally, we reevaluate the gallium anomaly, updating its global significance and presenting the most up-to-date status of its interpretation in terms of sterile neutrinos.

Noble element detectors using argon or xenon as the detection medium are widely used in the searches for rare neutrino and dark matter interactions. Xenon doping in liquid argon can preserve attractive properties of an argon target while enhancing the detectable signals with properties of xenon. In this work, we deployed a dual-phase liquid argon detector with up to 4% xenon doping in the liquid and studied its gas electroluminescence properties as a function of xenon concentration. At $\sim 2\%$ xenon doping in liquid argon, we measured $\sim 34\mathrm{ppm}$ of xenon in the gas and observed $\sim 2.5$ times larger electroluminescence signals using vacuum ultraviolet silicon photomultipliers than those in pure argon. Analysis of signals of different wavelengths confirms that the argon gas electroluminescence process is strongly modified by the addition of xenon. We propose an analytical model to describe the underlying energy transfer mechanism in argon-xenon gas mixtures. Lastly, the implications of this measurement for low-energy ionization signal detection will be discussed.

Using data samples of $988.4{\mathrm{fb}}^{-1}$ and $427.9{\mathrm{fb}}^{-1}$ collected with the Belle and Belle II detectors, we present a study of the singly Cabibbo-suppressed decays ${\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }\eta$, $\mathrm{\Lambda }{\eta }^{\prime }$, and $\mathrm{\Lambda }{\pi }^0$. We observe the decay ${\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }\eta$ and find evidence for the decay ${\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\eta }^{\prime }$, with corresponding branching ratios determined to be $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }\eta )/\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})=(4.16\pm 0.91\pm 0.23)\%$ and $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\eta }^{\prime })/\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})=(2.48\pm 0.82\pm 0.12)\%$, respectively. We find no significant signal in the ${\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\pi }^0$ decay mode and set an upper limit at the 90% credibility level of $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\pi }^0)/\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})<3.5\%$. Multiplying these ratios by the world-average branching fraction of the normalization channel, $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})=(1.43\pm 0.27)\%$, we obtain the absolute branching fractions of $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }\eta )=(5.95\pm 1.30\pm 0.32\pm 1.13)\times {10}^{-4}$, $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\eta }^{\prime })=(3.55\pm 1.17\pm 0.17\pm 0.68)\times {10}^{-4}$, and an upper limit at the 90% credibility level on the absolute branching fraction of $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{\pi }^0)<5.2\times {10}^{-4}$. The quoted first and second uncertainties are statistical and systematic, respectively, while the third uncertainties arise from the branching fraction of the normalization mode. These results are consistent with most theoretical predictions and further the understanding of the underlying decay mechanisms.

Dark sector models present a rich phenomenology that requires high-intensity beams and precision detectors for thorough exploration. The NA62 experiment has already published several constraints on dark sector models, leveraging proton beam dump and meson decay techniques. This proposal aims to demonstrate the NA62 detector discovery potential for dark sector candidates by using the positron-on-target technique. High-intensity secondary positron beams, reaching up to $\sim 150\mathrm{GeV}$ energy, have already been produced at the North Area extracted beam lines. If a positron beam with an intensity in the range of $2\times {10}^{14}$ positrons on target per year is delivered, the NA62 detector would be ideal for searches of dark sector particles in both visible and invisible decay channels. Additionally, positron on target collisions would enable precision measurements of key standard model observables, including a detailed scan of $\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-})$ and $\sigma (e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-})$ at the di-pion and di-muon production threshold, with discovery potential for the True Muonium $({\mu }^{+}{\mu }^{-})$ bound state.

Polymer models are effective in describing quantum gravity effects around the initial singularity, leading to its replacement by bouncing surfaces on which the curvature and densities are finite. Their properties depend on the space-time symmetry and on the particular polymerization scheme adopted. In this article we investigate anisotropic models under the Gambini-Benítez-Pullin polymerization, recently used to quantise spherically symmetric black-holes, whose interiors are isometric to Kantowski-Sachs (KS) space-times. Demanding that the minimum area defined by the bouncing surface matches the loop quantum gravity area gap, we can find its radius alongside the curvature and effective density and pressures at the bounce. The density is always positive, while the pressures are negative enough to avoid the singularity. Due to the positive spatial curvature, the solution is oscillatory, reaching a maximum radius where a recollapse occurs. Therefore, a positive cosmological constant is included in order to have an eternal expansion to a late de Sitter phase. We have also considered a Bianchi III metric, showing that the bounce is still present, but the space-time is asymptotically flat in this case, with no recollapse. In this hyperbolic space, the minimal area constraint can also be imposed on compact 2-surfaces. Nevertheless, in contrast to the KS case, it is enough for avoiding the singularity, independently of polymerization procedures.

The forthcoming space-based gravitational-wave observatory Laser Interferometer Space Antenna (LISA) should enable the detection of extreme mass ratio inspirals (EMRIs), in which a stellar-mass compact object gradually inspirals into a supermassive black hole while emitting gravitational waves. Modeling the waveforms of such systems is a challenging task, requiring precise computation of energy and angular momentum fluxes as well as proper treatment of orbital resonances, during which two fundamental orbital frequencies become commensurate. In this work, we perform a systematic comparison of fluxes derived from three approaches; the quadrupole formula, post-Newtonian approximations, and time-domain solutions of the Teukolsky equation. We show that quadrupole-based fluxes remain in good agreement with Teukolsky results across a broad range of orbital configurations, including perturbed orbits. Building on these insights, we explore the dynamical impact of resonance crossings within the adiabatic approximation. By introducing novel numerical methods, we reduce computational costs and uncover diverse resonance-crossing behaviors. These results contribute to the effort to understand theoretically and model adequately resonance crossings during an EMRI.