We extend our previous analysis [Phys. Rev. D 109, 065005 (2024)] of CPT-odd electromagnetic response in tilted, anisotropic Weyl semimetals to the overtilted (type-II) regime, where electron and hole pockets coexist at the Fermi level. Starting from the minimal QED sector of the Standard Model extension matched to a lattice-motivated anisotropic Dirac Hamiltonian with tilt, we compute the zero-temperature finite-density effective action nonperturbatively from the vacuum polarization tensor, and corroborate the result using a complementary chiral kinetic theory formulation that consistently incorporates both Fermi-sea and Fermi-surface contributions. In the type-II regime the unbounded linear dispersion necessitates a physical ultraviolet regularization. Implementing a hard momentum cutoff tied to the lattice bandwidth, we show that the CPT-odd, axionlike response remains finite across the type-I to type-II Lifshitz transition, while acquiring tilt- and anisotropy-dependent renormalizations together with nonuniversal, cutoff-sensitive terms governed by the geometry of the electron and hole pockets. As a concrete application, we evaluate the anomalous Hall conductivity in the prototypical type-II Weyl semimetal ${\mathrm{WTe}}_2$, using parameters extracted from first-principles calculations and experiments, and find that Fermi-sea and Fermi-surface contributions are comparable and partially cancel, yielding a finite and strongly anisotropic Hall response characteristic of the overtilted regime.

A quantum clock cannot be modeled as a point mass moving along a single geodesic if it is in a state with nonzero position fluctuations. Instead, it is an extended object subject to tidal forces and a superposition of time dilations at different altitudes. Here, a geometrical formulation of quantum mechanics is used to show that additional quantum properties representing correlations between different directions imply a non-Riemannian geometrical structure experienced by a quantum clock. A specific version of Finsler geometry parametrized by entropy and purity of the state provides a novel setting for a combination of quantum and gravitational effects. A crucial ingredient is given by a new parametrization of quantum-information properties related to second-order moments of a state and may also be useful in other applications.

We consider the general construction of near-horizon limit for extremal black hole solutions with nontrivial torsion, and derive the covariant geometric conditions for the existence this limit. A near-horizon solution with torsion is constructed in the case of extremal Kerr-AdS black hole, starting from an ansatz compatible with near-horizon symmetry. We demonstrate that this solution corresponds to the limit of a new black hole solution with torsion.

Oscillation modes of neutron stars, a key target for third-generation gravitational wave detectors, encode key information about their constituent nuclear matter. In this work, we study the effect of viscosity on oscillations of cold, polytropic, spherically symmetric neutron stars. We focus on purely radial oscillations and work perturbatively to linear order within two hydrodynamic frameworks: the acausal covariant generalization of the Navier-Stokes equations proposed by Eckart, and the causal generalization formulated by Bemfica, Disconzi, Noronha, and Kovtun (BDNK). We find that viscosity damps the radial modes on millisecond timescales and induces fractional shifts in the oscillation frequency which increase both with the compactness and viscosity of the star, reaching up to the percent level for the fundamental mode with bulk viscosities $\zeta \sim {10}^{30}\mathrm{g}/\mathrm{cm}/\mathrm{s}$. For more viscous stars, the oscillation frequency decreases, becoming zero (i.e., an overdamped mode) for $\zeta \gtrsim {10}^{31}\mathrm{g}/\mathrm{cm}/\mathrm{s}$. We also study the linear threshold of gravitational collapse. Consistent with recent analytic results in the zero heat conductivity limit, we find that viscosity in Eckart theory cannot stabilize an unstable inviscid star. We provide numerical evidence that viscosity in BDNK theory is similarly unable to prevent gravitational collapse, but it slightly modifies the threshold of collapse. Overall, our results advance our understanding of the impact of viscosity on the oscillation modes of neutron stars, a key component of viscous asteroseismology with next-generation gravitational wave detectors.

Gravitational lensing of gravitational waves (GWs) will become the next frontier in studying cosmology and gravity. While time-delay cosmography using quadruply lensed GW events associated with optical images of the lens systems can provide precise measurement of the Hubble constant ($H_0$), they are considered to be much rarer than doubly lensed events. In this work, we analyze time-delay cosmography with doubly lensed GW events for the first time. We generate mock doubly lensed GW events with the designed sensitivity of the LIGO-Virgo-KAGRA (LVK) O5 network, with the LIGO post-O5 upgrade, and with the Einstein Telescope $(\mathrm{ET})+\mathrm{Cosmic}\mathrm{Explorer}(\mathrm{CE})$ network, and we select the events that can be associated with future galaxy surveys. Over 1000 realizations, we find an average of $\sim 0.2(2.3)$ qualified events with the LVK O5 (post-O5) network, whereas with the $\mathrm{ET}+\mathrm{CE}$ network, we find an average of 80.9 qualified events over 100 realizations. Using the singular isothermal sphere (SIS) lens model, we forecast the constraints on cosmological parameters and modified GW propagation by combining time-delay cosmography and the standard siren approach. The average posterior gives a constraint on $H_0$ with relative uncertainties of 14%, 10%, and 0.42% in the $\mathrm{\Lambda }\mathrm{CDM}$ model for the LVK O5, LVK post-O5, and $\mathrm{ET}+\mathrm{CE}$ networks, respectively. While the LVK network gives uninformative constraints on the $(w_0,w_a)$ dynamical dark energy model, the $\mathrm{ET}+\mathrm{CE}$ network yields moderate constraints of $w_0=-1.02_{-0.25}^{+0.31}$ and $w_a=0.39_{-1.55}^{+1.01}$. In addition, our method can provide precise constraints on modified GW propagation effects jointly with $H_0$.

We perform a consistency check of DESI DR2 BAO constraints ($D_M/r_d,D_H/r_d$) by reconstructing the same quantities from DES supernovae (SNe) in bins with the same effective redshift $z_{\mathrm{eff}}\in \{0.510,0.706,0.934\}$ and a Planck $r_d$ prior. Through mock analysis we show that $D_M(z_{\mathrm{eff}})$ and $D_H(z_{\mathrm{eff}})$ can be locally reconstructed model agnostically from $\mathrm{\Lambda }\mathrm{CDM}$ and extended models, but only if one employs frequentist methods; purely Bayesian reconstructions from Markov chain Monte Carlo exhibit bias. We find that the ratio of the three $D_M/r_d$ values at different $z_{\mathrm{eff}}$ are consistent with a horizontal, thus confirming that the distance duality relation holds up to calibration. However, the $D_H/r_d$ ratio shows a decreasing trend driven by the $z_{\mathrm{eff}}=0.934$ bin, the significance of which varies from $2.5\sigma$ with Bayesian methods down to $1.4\sigma$ with frequentist methods. We show that replacing DES with DES-Dovekie SNe reduces the significance to $1.7\sigma$ and $1.2\sigma$ in Bayesian and frequentist approaches, respectively. We conclude that distances reconstructed from SNe show good agreement with DESI baryon acoustic oscillation (BAO) distances across the redshifts studied. We also note that $D_M(z_{\mathrm{eff}}=0.510)/r_d$ reconstructed from SNe favors DESI BAO over transversal BAO against a backdrop of a $3.7\sigma$ disagreement.

Tensions in late-time expansion data have renewed interest in models beyond $\mathrm{\Lambda }\mathrm{CDM}$. We ask: how isotropic must dark energy be? Working in Bianchi I, we allow time-dependent anisotropic stress and introduce a parametrization that enforces a vanishing line-of-sight integral of the shear, thereby satisfying the CMB integrated Sachs–Wolfe quadrupole bound by construction. Using $\mathrm{Pantheon}+\mathrm{SH}0\mathrm{ES}$ SNe together with Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillation (BAO) distances, single-bin (constant) and five-bin anisotropic models improve the fit over $w\mathrm{CDM}$ by $\mathrm{\Delta }(-2\ln {\mathcal{L}}_{\mathrm{iso}})=14.8$ and 26.6, respectively, but both violate the quadrupole constraint. In contrast, a five-bin constrained model achieves $\mathrm{\Delta }(-2\ln {\mathcal{L}}_{\mathrm{iso}})=15.4$ while remaining compatible with the quadrupole limit. The fit improvement arises from two sources: capturing directional structure in the $\mathrm{Pantheon}+\text{SNe}$ data, and partially alleviating the tension between the SH0ES $H_0$ value and DESI BAO distances.

The detection of the gravitational waves produced after the coalescence of two neutron stars is greatly anticipated because it will be able to provide information about matter in extreme conditions, especially if the remnant turns out to go through a hypermassive or a supermassive neutron star state before collapsing into a black hole. Next-generation gravitational wave detectors, such as the Einstein Telescope, the Cosmic Explorer, and the Neutron-star Extreme Matter Observatory are expected to observe high-frequency gravitational wave signals, that is, the postmerger stage of the coalescence of binary neutron stars; then from these signals one can estimate the maximum mass that a spinless neutron star (${\mathrm{M}}_{\mathrm{TOV}}$) can have. In this paper, we investigate the problem of the determination of the ${\mathrm{M}}_{\mathrm{TOV}}$ precision from the postmerger detected by next-generation observatories. Our results show that only under the most optimistic scenario of signal-to-noise ratio for post-merger signals ($\mathrm{SNR}\ge 8$) and merger rate density ($250{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$), CE 20 km achieves the highest mass precision in the range $\delta M/2\approx 0.1–0.3M_{\odot }$ for a remnant mass of $2.57M_{\odot }$ in five years of observation. We clarify that this precision represents the minimum uncertainty, corresponding to the most probable value (main peak) in the final mass distribution, showing that it depends on the value of the final (remnant) mass. Therefore, based on the results obtained in this study, it may still be necessary to improve the sensitivity at high frequencies of future ground-based gravitational wave observatories if one wants to obtain greater precision in the estimation of ${\mathrm{M}}_{\mathrm{TOV}}$. One possibility would be to improve the sensitivity in a frequency range that allows us to determine whether or not a black hole was formed or will be formed in the coalescence. The right choice of interferometer length and tunable design that optimizes detection at high frequencies is essential for a successful determination of ${\mathrm{M}}_{\mathrm{TOV}}$. Other lengths and tunable designs of interferometers, as well as sensitivity curves extended up to 10 kHz for both present versions of CE (since the reference used for CE provides these curves only up to 5 kHz), will be considered in future work, seeking to increase the number of postmerger detections in five years of observation and also determine the final merger product.

We present a new hadronic EoS with hyperons built within the relativistic mean-field (RMF) formalism with baryon-density- and isospin-density-dependent couplings. Motivated by microscopic calculations showing density- and isospin-asymmetry-dependence of self-energies, we implement a new form for the baryon-meson couplings. The parameters for the couplings are constrained by a Bayesian analysis, which anchors the model to nuclear saturation properties, chiral effective field theory ($\chi \mathrm{EFT}$) predictions for pure neutron matter, heavy-ion collision data, and HALQCD-based hyperon potential calculations at 3-momentum $|\mathbf{k}|=0$ in both isospin-symmetric and pure neutron matter. The resulting EoS satisfies neutron star mass-radius constraints from NICER and GW170817, providing another way to address the hyperon puzzle. The low-density part of the EoS is described via nuclear statistical equilibrium with modern mass tables (AME20/FRDM12, 8244 nuclei), providing a novel and complete general-purpose EoS for astrophysical simulations.

Neutrino interactions play a central role in transport and flavor evolution in the ejecta of binary neutron star mergers. Simulations suggest that neutron star mergers may produce magnetic fields as strong as ${10}^{17}\mathrm{G}$, but computational difficulties have hampered the inclusion of magnetic field effects in neutrino interaction rates. In this paper we give approximate interaction rates for neutrinos in the presence of strong magnetic fields, including the effects of Landau quantization and anomalous magnetic moments with errors of order $\sqrt{T/M}$. We also comment on a neutrino production channel from individual neutrons that can produce low-energy $\nu \overline{\nu }$ pairs of all three flavors even at low density.

We present an approximate energy-integration method for identifying collisional neutrino flavor instabilities. Direct evaluation of the dispersion relation requires multidimensional integrals over neutrino phase space, making systematic searches for unstable modes in numerical models of core-collapse supernovae (CCSNe) and binary neutron star mergers (BNSMs) computationally expensive. In the literature there are some approximate schemes, but they are largely restricted to the homogeneous limit and can exhibit inaccuracies as reported in recent studies. In the current paper, we clarify the origin of the limitations in previous schemes and provide a better approximation method that robustly preserves the key physics of spectral asymmetries and collision rates. It yields a reduced dispersion relation that is inexpensive to evaluate. Comparison with exact solutions demonstrates that our new approximate method shows a good performance in computing both real frequencies and growth rates across a wide range of regimes, including isotropic and anisotropic neutrino distributions for both homogeneous and inhomogeneous modes. This provides a practical, accurate, and scalable framework for identifying collisional flavor instabilities in high-energy astrophysical simulations such as CCSNe and BNSMs.

The accurate modeling of Earth matter effects is a critical systematic consideration for precision measurements of the $CP$-violating phase ${\delta }_{CP}$ in long-baseline neutrino oscillation experiments. We investigate the extent to which constant and path-averaged density approximations are sufficient for reproducing the ${\nu }_{\mu }\to {\nu }_e$ appearance probabilities predicted by the preliminary reference Earth model (PREM) across baselines ranging from $L=1000\mathrm{km}$ to $L=12000\mathrm{km}$. Using a full three-flavor matrix exponentiation framework with spatially resolved PREM density profiles, we demonstrate that the constant density approximation introduces a negligible bias of less than 0.3° in the reconstructed ${\delta }_{CP}$ for baselines up to $L\approx 5000\mathrm{km}$, but undergoes a sharp increase beyond this threshold, reaching 17.8° at $L=7000\mathrm{km}$ and 172.2° at $L=12000\mathrm{km}$. We show that this bias arises from energy-dependent distortions in the oscillation probability produced by the Earth’s internal density layering, which generate degeneracies between matter-induced and intrinsic $CP$-violating contributions to the appearance channel that cannot be removed by marginalizing over a single effective density. These results demonstrate that the constant density approximation is not a conservative simplification but a source of fundamental systematic error at long baselines, and motivate the incorporation of spatially resolved Earth density treatments, such as PREM, in the analysis frameworks of next-generation long-baseline neutrino oscillation experiments.

Dark matter detection experiments using liquid argon rely on a precise characterization of the ionization response to nuclear recoils, especially in the keV energy range relevant for light dark matter interactions. In this work, we present a comprehensive analysis that combines new measurements from the ReD setup, part of the DarkSide experimental program, with calibration data from DarkSide-50, as well as results from the ARIS and SCENE experiments. These combined datasets enable improved constraints on atomic screening effects in the modeling of the ionization response of liquid argon to nuclear recoils. The analysis is performed within the Thomas-Imel recombination framework adopted in previous DarkSide studies, and is here further constrained by the inclusion of ReD data, which allow the screening function to be determined from calibration measurements. By including the updated ionization model into the DarkSide-50 analysis framework, we obtain stronger exclusion limits on low-mass weakly interacting massive particle (WIMP) interactions, setting new world-leading constraints in the $1–3\mathrm{GeV}/{\mathrm{c}}^2$ WIMP mass range. Finally, we recast the sensitivity projections for the upcoming DarkSide-20k detector, demonstrating a significantly enhanced discovery potential for low-mass dark matter candidates.

Searches for axion and axionlike dark matter based on solid-state spin qubits are fundamentally limited by strong longitudinal dephasing, which rapidly suppresses the sensitivity gains offered by entanglement. Here, we show that quantum error correction (QEC) can substantially enhance axion search sensitivity in realistic semiconductor spin qubit platforms by mitigating this dominant noise source. By integrating an optimally chosen repetition code QEC with logical Green berger–Horne–Zeilinger block entanglement, we derive closed-form expressions for the quantum Fisher information that explicitly incorporate the finite coherence time of the axion field. Our analysis demonstrates that modest QEC cycle frequencies are sufficient to significantly reduce the effective dephasing rate, thereby restoring a broad parameter regime in which entanglement-enhanced sensing surpasses the standard quantum limit. Projecting these results onto complementary metal-oxide semiconductor-compatible device parameters, we find that QEC-protected entangled sensing can revive otherwise inaccessible quantum advantages, yielding up to order-of-magnitude improvements in sensitivity to the axion-electron coupling $g_{ae}$. These results establish a practical and theoretically controlled pathway for using QEC to improve qubit array searches for physics beyond the standard model.

We study the Duan-Giedke-Cirac-Zoller continuous-variable inseparability criterion in a weakly relativistic, single-pair Klein-Gordon model of two charged scalar mesons. We implement a nonrelativistic inseparability criterion to quasirelativistic Klein–Gordon bound states, evaluated in the relativistic center-of-mass frame, where canonical position and momentum operators remain meaningful approximate observables. We assumed that the distance between the mesons exceeds the radius of the short-range strong interaction, which is of the order of 2-3 femtometers. Therefore, the dominant interaction in the system is a central-symmetric Coulomb potential. In particular, we utilized the sufficient criterion for separability and the necessary condition of inseparability to calculate the total variance of two operators in the weakly relativistic and nonrelativistic cases. In the weakly relativistic case, we used the solution of the Klein-Gordon equation. In contrast, in the nonrelativistic case, we used the solution of the Schrödinger equation obtained for the same central-symmetric potential. Within this regime, the Klein-Gordon states considered show a stronger violation of the separability bound than the corresponding Schrödinger states.

We investigate the behavior of Einstein crystals in noncommutative backgrounds described by the Snyder and Snyder–de Sitter models. Possible novel effects, which may arise in realistic systems such as diamond crystals, are analyzed within a thermodynamical framework. We show that noncommutativity influences the key thermodynamic quantities, including internal energy and specific heat. These corrections can be directly related to modifications of the underlying uncertainty relations, of the generalized uncertainty principle (GUP) and generalized extended uncertainty principle (GEUP) types.

In this work, we derive the propagator of a massive charged vector boson in the presence of a homogeneous and constant magnetic field of arbitrary strength, working in the unitary gauge and in the mostly minus metric. The propagator is constructed using the Ritus eigenfunction method, which allows for an explicit treatment of Landau-level quantization and spin degrees of freedom. We present a detailed analysis of the polarization vectors for all Landau levels. Using the Ritus representation, we formulate and derive the LSZ reduction formula for massive charged vector bosons in a magnetic field background, providing a useful tool for the calculation of self-energies and radiative corrections with external charged states. Furthermore, we establish a systematic connection between the Ritus’s eigenfunctions and Schwinger proper-time representations of the propagator, identifying Schwinger’s phase and exhibiting a slight discrepancy with previous results in the literature that arise in the unitary gauge, highlighting the importance of a careful treatment of spin and gauge structures in an external magnetic field.

In a $U(1{)}_{R-L}$-symmetric supersymmetric model, pseudo-Dirac bino and wino can act like right-handed neutrinos, generating the light neutrino masses through a hybrid type I + III inverse seesaw mechanism. We investigate such a model to accommodate the baryon asymmetry of the universe together with neutrino masses. A pseudo-Dirac gaugino goes under particle-antiparticle oscillations. Possible $CP$ violation in bino decays, induced by mixing with the neutrinos, can be enhanced in bino–antibino oscillations. Focusing on a long-lived bino, we show that its oscillations and decays can generate the observed baryon asymmetry while the wino is responsible for generating the neutrino masses. This mechanism requires a decoupled mass spectrum with a bino of mass $M_{\tilde{B}}\sim \mathcal{O}(\mathrm{TeV})$ and sfermions with mass $M_{\mathrm{sf}}\gtrsim 50\mathrm{TeV}$. Furthermore, for the bino to decay out-of-equilibrium before the electroweak sphalerons turn off, the messenger scale needs to be ${\mathrm{\Lambda }}_M\sim \mathcal{O}({10}^7\mathrm{TeV})$. We discuss the displaced vertex signals at the LHC resulting from such a high messenger scale.

In recent years, the ATOMKI collaboration has performed a series of measurements of excited nuclei, observing a resonant excess of electron-positron pairs at large opening angles compared to the Standard Model prediction. The excess has been hypothesized to be due to the production of a new spin-1 or spin-0 particle, $X$17, with a mass of about 17 MeV. Recently, the PADME experiment has reported an excess in the $e^{+}{e}^{-}$ cross section at center-of-mass energies near 17 MeV, perhaps further hinting at the existence of a new state. Studies of the spin-1 case have hitherto focused on either vector or axial-vector couplings to quarks and leptons, whereas UV theories more naturally produce both vector and axial-vector (i.e., chiral) couplings, analogous to the Standard Model weak interactions. We consider the ATOMKI anomalies in the context of an $X$ with chiral couplings to quarks and explore the parameter space that can explain the ATOMKI anomalies, contrasting them with experimental constraints. We find that it is possible to accommodate the reported ATOMKI signals. However, the 99% confidence level region is in tension with null results from searches for atomic parity violation and direct searches for new low mass physics coupled to electrons. This tension is found to be driven by the magnitude of the reported excess in the transition of ${}^{12}\mathrm{C}(17.23)$, which drives the best-fit region toward excluded couplings.

We consider nuclear gamma decays and $\gamma$-emitting reactions that can be an efficient source of hypothetical millicharged particles ($\chi$). In particular, we revisit the production of millicharged particles in nuclear reactor environment, pointing out that $\gamma$ cascades from ${}^{239}\mathrm{U}$ is an overlooked yet a powerful source of $\chi \overline{\chi }$ pairs. This leads to an increased flux compared to previous studies. We then apply new estimates of the flux to derive novel limits on the value of millicharge, $ϵ=Q_{\chi }/e$, from the electron recoil searched for in a variety of experiments placed in proximity to the reactor cores. The derived limits on $ϵ$ are the strongest in the interval of masses $\sim 0.7–2\mathrm{MeV}$. We also derive the millicharged particles flux from the Sun and point out potential sensitivity of the low-threshold dark matter search experiments.