We demonstrate that a background rotation significantly catalyzes the chiral magnetovortical instability in chiral magnetohydrodynamics. The rotation splits the linearly polarized Alfvén wave into two circularly polarized magneto-Coriolis waves, one of which exhibits a lower frequency than the original Alfvén wave. We find that this low-frequency magneto-Coriolis wave is always unstable in the presence of even a weak chiral vortical effect. This instability may enable new dynamo mechanism applicable to various rotating chiral plasmas.

A search for resonant structures in the $J/\psi +\psi (2\mathrm{S})$ mass spectrum is performed using proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$, corresponding to an integrated luminosity of $140{\mathrm{fb}}^{-1}$, recorded by the ATLAS experiment at the LHC. The decay channels of $J/\psi +\psi (2\mathrm{S})\to 4\mu$ and $J/\psi +\psi (2\mathrm{S})\to 4\mu +2\pi$ are analyzed. An excess near 6.9 GeV is observed in both channels with a combined significance of $8.9\sigma$. No significant signal is observed near 7.2 GeV, and an upper limit on its yield relative to $X(6900)$ is provided. A simultaneous fit with the di-$J/\psi$ channel is carried out under assumptions regarding the resonance interferences, yielding a ratio of the partial decay widths between the $J/\psi +\psi (2\mathrm{S})$ and di-$J/\psi$ channels of $1.08\pm 0.20_{-0.17}^{+0.40}$ for the resonance near 6.9 GeV.

The ${\mathrm{JSNS}}^2$ (J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source) experiment at the Material and Life Science Facility (MLF) of J-PARC is designed to directly test an excess on ${\overline{\nu }}_e$ events which was indicated by the Liquid Scintillator Neutrino Detector (LSND). The combination of a short-pulsed proton beam and a gadolinium-loaded liquid scintillator provides an excellent signal-to-noise ratio. In this article, we report the first results of a direct test based on data collected in 2022. After applying all event selection criteria, two events are observed, consistent with the expected background of $2.3\pm 0.4$ events. No excess of ${\overline{\nu }}_e$ events are seen in this report, however the expected number of events due to LSND anomaly is $1.1\pm 0.5$, thus this result is not yet conclusive. Data taking has been ongoing since 2021 and will continue in future runs. In addition, a new far detector has recently been constructed for the second phase experiment, ${\mathrm{JSNS}}^2$-II, marking an important milestone toward forthcoming measurements.

Twin stars, i.e., pairs of compact stars with identical masses but distinct radii, have long been considered a potential signature of a phase transition in dense QCD matter. Using a model-agnostic equation-of-state (EOS) inference setup, we show that once constraints from chiral effective field theory, perturbative QCD, and current multimessenger observations are simultaneously imposed, such solutions are strongly suppressed. The remaining viable EOSs occupy two highly fine-tuned regions in parameter space, characterized by either a discontinuous early onset phase transition or a rapid crossover at higher density, the latter coupled with a distinctive double-peaked speed of sound. Given that neither class features a conformalization of the EOS upon entering the second branch, we argue that the standard twin-star scenario linking the mass-radius discontinuity to deconfinement can be effectively ruled out.

Harada’s recently announced Kerr-Schild solution of Einstein’s equations in general relativity [Phys. Rev. D 112, 024020 (2025)] is identified as isometric with one of the well-known NUT solutions.

We introduce waveletnet, a wavelet-based neural-network architecture for identifying non-Gaussian noise in gravitational-wave data and reducing its impact on candidate ranking. Traditionally, convolutional neural networks (CNNs) have been widely used as a flexible machine learning method to mitigate non-Gaussian noise. However, training CNNs requires many data samples, especially when the input data segments are long. Glitches that mimic high-mass black hole signals are empirically known to have a waveletlike structure. We exploit this property in waveletnet by using simple neural networks to learn the best family of wavelets to model glitches in the LIGO-Virgo-KAGRA O3 data. Due to its simplicity, our framework is significantly more sample-efficient than CNNs. As a use case, we build upon the trigger inference using the extended strain representation (TIER) method from [arXiv:2507.08318] and show waveletnet can improve the performance of search pipelines. We take potential GW candidates from the pipeline, and then downweight the candidates having noisy strain regions in their vicinity [i.e., within $t_{\text{candidate}}\pm \mathcal{O}(10)\sec$]. We use our framework in a modular way: we provide an output score that can be added to the pipeline’s existing detection statistic for the candidates. We test our method using candidates from the ias-hm search pipeline and find peak improvements of $\sim 15\%$ in the search sensitive volume, concentrated at high total masses and asymmetric mass ratios.

The theory of gravitational wave turbulence describes the long-term statistical behavior of a set of weakly nonlinear interacting waves. In this paper, we aim to study aspects of gravitational turbulence within the framework of general relativity using the Hadad-Zakharov metric. The latter is parametrized by four functions (the coefficients of a diagonal metric) that must satisfy seven nontrivial Einstein equations, six of which are independent. The issue of their mutual compatibility is therefore essential, yet it has so far been overlooked. In this work, we argue that these equations can be compatible in the weakly nonlinear regime under specific conditions. Our analytical investigation is complemented by direct numerical simulations performed with a new graphics processing unit-based code, tiger. A comparative analysis of the evolution of the Ricci and Kretschmann scalars indicates that gravitational wave turbulence corresponds to the propagation of a genuine physical degree of freedom. These numerical findings, however, must be interpreted with caution, given the difficulty of satisfying all seven Einstein equations simultaneously with sufficient accuracy. On the other hand, our simulations reproduce well the expected properties of the wave turbulence regime, with the emergence of a dual cascade of energy and wave action, and for the latter the observation of the Kolmogorov-Zakharov spectrum. In addition, our analysis reveals that the canonical variables of the problem evolve toward a nearly Gaussian statistical distribution punctuated by intermittent coherent (spatially localized and long-living) structures. In contrast to the canonical variables, the structure functions of the gauge-invariant metric components exhibit monofractal behavior, which is a classical property of wave turbulence.

We investigate the stability and gravitational waves (GWs) in the four-dimensional general Einstein-vector theory on a cosmological background. To study the stability, we systematically perform a Hamiltonian analysis at the linear perturbation level. The stability conditions are easily satisfied for tensor perturbations, but they impose nontrivial constraints on the parameter space for vector and scalar perturbations. In particular, in the presence of a nonzero background vector field, the scalar sector fails to satisfy the stability conditions in the general parameter space. However, imposing the plane-wave condition relaxes these conditions, making them achievable. In the small-scale limit, we further investigate the GW properties of the general Einstein-vector theory within the stable parameter space, including the number of independent modes, their propagation speeds, and observational constraints from GW experiments. We find that there can be at most two tensor modes, two vector modes, and one scalar mode. Notably, without imposing the plane-wave ansatz, no scalar GWs exist within the stable parameter space. Furthermore, vector GWs are forbidden if tensor GWs propagate exactly at the speed of light.

Motivated by the cosmological collider program, which aims to probe high-energy physics through inflation, we investigate the phase diagram of multiflavor QCD in de Sitter spacetime with a flavor-universal axial chemical potential induced by a rolling inflaton coupled to fermions. We determine the first-order critical line and a critical point as functions of the Hubble parameter and the axial chemical potential, employing an effective description of chiral symmetry breaking within the framework of the Nambu–Jona-Lasinio model. We find that a first-order chiral phase transition may occur during inflation or at its end when the axial chemical potential is sufficiently large and crosses the critical line. This serves as a benchmark cosmological analog of the QCD phase diagram explored in heavy-ion colliders.

We study the prospects of the Lunar Gravitational-Wave Antenna (LGWA), a proposed deci-Hz GW detector, to observe binary black holes (BBHs) and enable multiband science with ground-based detectors. We assess the detectability of the events observed by current instruments up to the Gravitational-Wave Transient Catalog 4.0 data release, and of simulated populations consistent with the latest reconstruction by the LIGO-Virgo-KAGRA Collaboration. We find that the LGWA alone would have been able to observe more than one-third of the events detected so far, and that it could detect $\sim 90$ events merging in the ground-based band per year out to redshifts $z\sim 3–5$. Current detectors at design sensitivity and 100% duty cycle could detect thousands of BBHs per year, with one to a few hundred multiband counterparts in the LGWA. Third-generation (3G) detectors can observe most of the BBHs detected by the LGWA merging in their frequency band in the simulated mass range $7M_{\odot }\lesssim M_{\mathrm{tot}}\lesssim 600M_{\odot }$, enabling systematic joint analyses of hundreds of events. The short time to merger from the deci-Hz band to the Hz-kHz band (typically months to a year) allows for early warning, targeted follow-up, and archival searches. Multiband observations of intermediate-mass BBHs in the deci-Hz band are particularly promising. We perform an injection study for a GW231123-like system (the most massive BBH detection to date, which accumulates $\sim {10}^5$ inspiral cycles in the LGWA) and show that deci-Hz observations can measure the chirp mass even better than 3G instruments and yield good sky localization and inclination measurement, even with a single observatory. Opening the deci-Hz band would substantially improve the prospects of GW astronomy for intermediate-mass BBHs.

Direct searches of dark matter candidates with mass energies less than 1 GeV is an active research field. The energy depositions are comparable to the scale of atomic, molecular, or condensed matter systems, therefore many-body physics plays an important role in understanding the detector’s response in dark matter scattering. We present in this work a comprehensive dataset of atomic response functions for xenon and germanium with 12.2 and 80 eV energy thresholds, respectively, using the (multiconfiguration) relativistic random phase approximation. This approach takes into account the relativistic, exchange, and correlation effects in one self-consistent framework, and is benchmarked successfully by photoabsorption data from thresholds to 30 keV with $\lesssim 5\%$ errors. Comparisons with our previous and some other independent particle approaches in literature are made. It is also found that the spin-dependent (SD) response has significant difference from the spin-independent (SI) one such that the dark matter SD and SI interactions with electrons can be distinguished in unpolarized scattering, which is typical for direct search detectors. Finally, the exclusion limits set by current experiments are updated with our new results.

Early warning of gravitational waves (GWs) is essential for multimessenger observations of binary neutron star and black hole-neutron star merger events. In this study, we investigate early warning prospects from eccentric compact binaries, whose mergers are expected to comprise a significant fraction of detected GW events in the future. Eccentric binaries exhibit oscillatory frequency evolution, causing GW frequencies to recur multiple times through their coalescence. Consequently, generating eccentric waveform templates for early warning requires specification of initial conditions. While the standard approach involves initiating waveform generation when the orbit-averaged frequency enters the detector band, we compare this with an alternative approach that uses the periastron frequency as the starting point. Our analysis shows that initializing at the periastron frequency yields an improved signal-to-noise ratio and sky localization. Additionally, including subdominant modes alongside the dominant (2, 2) mode leads to further improvements in sky localization. We explore the parameter space of primary mass $m_1\in [1.4,15]M_{\odot }$, spin ${\chi }_1\in [0,0.8]$, and eccentricity $e\le 0.4$ across three detector configurations: O5, Voyager, and 3G. We find that in the O5 configuration, including eccentricity and subdominant modes, the sky localization area can be reduced by 2%–80% at 1000 square degrees (from $e_5=0.1$ to $e_5=0.4$), offering up to 41 seconds of additional early warning time. For neutron star-black hole (NSBH) systems, subdominant modes alone contribute up to 70% reduction. For the Voyager configuration, the sky area reduction due to eccentricity spans 2%–85%, with eccentricity increasing from 0.1 to 0.4, yielding up to 1 minute of extra early warning time at 1000 sq. deg. sky area. Subdominant modes contribute up to 94% reduction for NSBH systems, though their impact is nearly zero for binary neutron star systems. In the 3G detector scenario, the sky area reduction due to eccentricity reaches 80% (from $e_{2.5}=0.1$ to $e_{2.5}=0.4$) at 100 square degrees, and subdominant modes enhance the reduction up to 98% for NSBH systems.

We investigate propagation of generic waves on thin planar domain walls effectively described by the scalar Dirac-Born-Infeld model (DBI). We pay a particular attention to the possibility of caustic formation—the process, which may lead to intensive particle emission by domain walls. It is demonstrated that no singularities arise in DBI in two-dimensional (2D) flat spacetime in the hyperbolic case, if one starts from smooth initial conditions. Technically, this happens because the same family characteristics of the relevant partial differential equation remain parallel at all the times, albeit not being straight lines generically. Crucially, characteristic curves cease to be parallel beyond the simplified setup of DBI in 2D flat spacetime. In particular, this is shown to be the case in $D>2$ for spherical waves, in an expanding Universe, and in the case of a minimal deformation of DBI necessary for avoiding the domain wall problem in cosmology. However, we prove that DBI remains caustic free in the hyperbolic case in all these physically relevant situations. This strongly suggests that caustics can form on planar domain walls only due to the loss of hyperbolicity, and they have a cusp profile. We demonstrate how the nontrivial structure of DBI characteristics beyond the 2D flat spacetime setup uncovered in this work can significantly affect cusp formation.

Using a hadronic framework, we derive an explicit expression for photon production from neutral pions in a weak background magnetic field. Our calculation is built on the proton triangle diagram with an effective Yukawa ${\pi }^0$-proton coupling, offering an alternative to quark-level descriptions that is advantageous when the magnetic length greatly exceeds the proton size. Corrections to the pion decay constant are computed up to second order in the magnetic-field strength, revealing that the field generally suppresses the decay rate. Quantitatively, however, the effect remains modest even for fields as strong as $|eB|\simeq m_{\pi }^2$. The differential photon emission rate exhibits anisotropy, with the strongest suppression occurring when the pion momentum is perpendicular to the magnetic field. Overall, the modification of the ${\pi }^0\to \gamma \gamma$ rate is parametrically small, scaling as $|eB{|}^2/m_P^4$, where $m_P$ is the proton mass. While the magnetic-field-induced anisotropy is conceptually interesting in principle, it is likely too small to be resolved in present heavy-ion measurements.

The determination of the neutrino mass ordering is one of the flagship goals in particle physics. A well-known and powerful synergy emerges when combining high-precision measurements of the effective atmospheric mass-squared splitting from electron antineutrino disappearance in reactor experiments with that from muon (anti)neutrino disappearance in accelerator-based long-baseline experiments. To fully exploit this synergy, percent-level precision in the atmospheric mass splitting is required—a target that JUNO is expected to achieve within a few months of data taking. This motivated the formulation of a mass ordering sum rule for neutrino disappearance channels, which shows that by combining data from T2K and NOvA with JUNO after one year of operation, the neutrino mass ordering can be determined at the $3\sigma$ confidence level. Since JUNO has recently started taking data, it is timely to ask whether this sum rule remains robust in the presence of new physics. We identify the necessary conditions for new physics to affect the sum rule and demonstrate that, in some cases, such effects could lead to an incorrect inference of the mass ordering. As concrete examples, we consider scalar nonstandard interactions (SNSI) and neutrinos coupled to an ultralight scalar field. We find that, for SNSI, current constraints render any modification of the sum rule negligible, whereas in the latter case, the inference of the ordering requires caution. Nevertheless, these effects can be disentangled, illustrating how the sum rule can also be used to search for new physics.

The gallium anomaly has a global significance of greater than $5\sigma$. While SM solutions are not strongly favored, most viable BSM solutions likewise run into strong tensions with reactor and solar neutrino data. In this work, we first emphasize that elastic scattering alone is insufficient to test and resolve the GA. Therefore, we require a detector with a calibrated neutrino source to precisely determine the incoming neutrino energy, avoid radiochemical extraction biases, and isolate oscillation-based effects. We propose to use charged-current neutrino capture on indium (${}^{115}\mathrm{In}$) as a target as it offers a low threshold (114 keV) and reasonably high cross section. The triple coincidence provided by ${}^{115}\mathrm{In}$ neutrino capture can be fully exploited by an opaque scintillation detector that also provides energy and position information. Recent successful research and development by the LiquidO Collaboration makes our proposal realistic and timely. We show that a 100 ton indium target combined with two source runs of a 3.4 MCi ${}^{51}\mathrm{Cr}$ source can probe the complete parameter space of the gallium anomaly, both in the context of a vanilla sterile neutrino as well as more involved BSM scenarios.

We perform a physics-informed Bayesian analysis of the equation of state (EOS) of hybrid neutron stars that incorporates color-flavor-locked quark matter modeled by a three-flavor nonlocal Nambu-Jona-Lasinio framework with vector repulsion and diquark pairing. Contrary to the model-agnostic Bayesian analyses, our scheme allows for distinguishing between the scenarios of neutron stars with quark cores and without them. The used quark model realizes asymptotic conformality at high densities in accordance with perturbative QCD. The hadronic sector is described by the density-dependent relativistic functional DD2Y-T, which satisfies chiral effective field theory constraints and includes hyperonic degrees of freedom. We construct a large set of candidate hybrid EOSs by varying the vector and diquark couplings and apply a Maxwell construction for the quark–hadron phase transition. Observational constraints from recent NICER pulsar mass–radius measurements and tidal deformability from GW170817 are incorporated into the likelihood. Depending on whether the observational data from the black widow pulsar PSR J0952-0607 and the HESS J1731-347 object are included to the analysis or not, the posterior distribution favors vector and diquark couplings around $({\eta }_V,{\eta }_D)\simeq (0.82,0.40)$ or $({\eta }_V,{\eta }_D)\simeq (0.64,0.36)$, respectively. This corresponds to equations of state that support two-solar-mass neutron stars with superconformal speed of sound and relatively low onset densities for deconfinement. Our findings indicate that the most probable hybrid EOSs are statistically preferred over the purely hadronic baseline. The corresponding probabilities of agreeing with the observational data differ by one or two orders of magnitude depending on the data set used. This suggests that quark cores may exist in all observed neutron stars.

We investigate dilepton production from an isospin-asymmetric hot and dense medium in order to explore the role of isospin imbalance in electromagnetic spectral properties. We focus in particular on modifications of the dilepton production rate associated with the onset of pion condensation, which can occur in the presence of a finite isospin chemical potential. We employ the Nambu–Jona-Lasinio model with isoscalar-vector interaction. We examine the phase structure in the $T-{\mu }_I$ plane and estimate the vector current correlator-resummed dilepton rate for an effective quark chemical potential. We find that the interplay between isospin asymmetry, pion condensation, and vector interactions leads to nontrivial modifications of the dilepton yield. In particular, we observe two key features of the pion condensed phase: an enhancement at lower invariant mass and a prominent plateaulike structure which also help clearly identify the pion condensed phase from a chirally broken/restored phase. These results highlight the potential sensitivity of dilepton observables to pion-condensed phase of QCD matter, with possible implications for future low-energy heavy-ion collision experiments as well as isospin-rich environments such as neutron star matter.

In this work, we investigate the behavior of the light vector $\rho$ meson in the presence of a symmetric nuclear medium at zero temperature. We calculate the mass, decay constant of the $\rho$ meson, and leading twist distribution amplitudes (DAs) in the light-front quark model in vacuum, which are further investigated at different baryonic densities. We also predict the Mellin moments of the DAs and decay width of the ${\rho }^0\to e^{+}{e}^{-}$ process in both vacuum and medium. The evolution of DAs is carried out by the leading order (LO) Efremov-Radyushkin-Brodsky-Lepage method and compared with available predictions. For better understanding of medium effects on the $\rho$ meson, we have also predicted the in-medium charge [$G_C(Q^2)$], magnetic [$G_M(Q^2)$], and quadrupole [$G_Q(Q^2)$] form factors. The in-medium charge radii, magnetic moment, and quadrupole moment have also been predicted in this work. We have found that the nuclear medium induces appreciable modifications on the mass, weak decay constant, decay width, and distribution amplitudes of the $\rho$ meson. However, the charge radii, magnetic moment, and quadrupole moment are observed to exhibit weaker sensitivity to changes in baryonic density.

Using a data sample of $427.9{\mathrm{fb}}^{-1}$ collected by the Belle II detector at or near the $\mathrm{\Upsilon }(4S)$ and $\mathrm{\Upsilon }(10753)$ resonances, the cross sections for $e^{+}{e}^{-}\to h^{+}{h}^{-}J/\psi (h=\pi /K/p)$ at center-of-mass energies ranging from 3.8 GeV or the production threshold to $5.5/6.0/7.0\mathrm{GeV}$ have been measured via initial-state radiation. The cross sections for the processes $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$ and $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ are consistent with previously published results. The cross sections for these channels obtained by combining with previous Belle results are also given. The process $e^{+}{e}^{-}\to p\overline{p}J/\psi$ is investigated for the first time. The yields are small and no significant structure is observed in the cross section versus energy. Searches for vector charmoniumlike states in the $h^{+}{h}^{-}J/\psi$ systems, and for associated intermediate states in the $h^{\pm }J/\psi$ systems, are also presented.