By using Wald formalism, we show that the identification between the bulk and boundary conserved quantities induced by the perturbation of generic nonelectromagnetic matter field holds not only on top of the asymptotically flat stationary spacetimes but also on top of the asymptotically AdS stationary ones. We further show that such an identification reduces to the familiar form for the test point particle by viewing it as the limiting case of general matter.

We revisit the quasinormal-mode and greybody factor correspondence for Kerr black holes in the eikonal limit and develop a systematic Wentzel–Kramers–Brillouin (WKB)-based formulation by recasting the radial Teukolsky equation into a Schrödinger-type equation with a short-range potential. Building on earlier studies of the correspondence in rotating backgrounds, we extend the analysis to gravitational perturbations and incorporate higher-order WKB corrections beyond the leading eikonal approximation. For gravitational perturbations, the predicted greybody factors are in good agreement with numerical results obtained from the generalized Sasaki-Nakamura equation, with increasing accuracy at large angular quantum number. We also identify the breakdown of the correspondence in the superradiant regime, where the WKB assumptions cease to be valid.

Compact binary systems that emit gravitational waves (GWs) are expected to exhibit orbital eccentricity together with generic spin configurations, leading to the precession of the orbital angular momentum, the individual spins, and the orbital plane around the total angular momentum. Although eccentric binaries with aligned spins have been extensively studied, closed-form post-Newtonian (PN) expressions that simultaneously capture both eccentricity and precessing-spin effects have remained unavailable. The presence of eccentricity significantly complicates orbital evolution, since solving the coupled differential equations generally requires numerical integration, thereby slowing waveform generation. In this work, we exploit the separation of timescales between the orbital motion, spin precession, and radiation reaction, and employ the precession-averaging method introduced by Morras et al. to effectively “average away” the explicit time dependence from the spin-orbit and spin-spin dynamics up to the second PN order. Building on this framework, we derive analytic phasing formulas from the evolution equations for the orbital frequency and eccentricity, treating eccentricity as a small parameter. Closed-form solutions for the eccentricity evolution and gravitational-wave phase are obtained up to the eighth power of the initial eccentricity $e_0$. The TaylorT2 approximant is generalized to incorporate spin-precession effects, and the orbital phase is calculated in both the time and frequency domains. To further enhance applicability, a resummation is performed on the TaylorT2 phasing formula to improve accuracy for moderate to high initial eccentricities. Taken together, these results provide efficient, closed-form phasing expressions that consistently capture the interplay of eccentricity and precessing spins, thereby enabling accurate and computationally tractable GW modeling for data analysis.

We show that in single-scalar theories of the form $\mathcal{L}=F(\mathrm{\Phi },X)R+G(\mathrm{\Phi },X)$, a generic nonminimal coupling $F(\mathrm{\Phi },X)$ induces, in the scalar-comoving frame, an additional transverse contribution to the effective heat flux, proportional to $(F_X/8\pi F)V_{\perp a}$, where $V_a\equiv {h_a}^c{\nabla }_c{\nabla }_{d}X{u}^d$ and $V_{\perp a}$ denotes the component orthogonal to the four-acceleration $a_a$. This term cannot in general be written as a spatial temperature gradient, and therefore obstructs a standard Eckart interpretation of the scalar sector for arbitrary timelike scalar configurations. As a result, requiring an Eckart heat flux $q_a=-K(D_a{T}_g+T_g{a}_a)$ for all such configurations is possible if and only if $F_X(\mathrm{\Phi },X)\equiv 0$, i.e., $F(\mathrm{\Phi },X)=F(\mathrm{\Phi })$, resulting in a theory that is a subclass of Horndeski. Thus, only Jordan-like theories of the type $F(\mathrm{\Phi })R+G(\mathrm{\Phi },X)$ admit a global Eckart fluid picture of the scalar sector, while models with $F_X\ne 0$ can recover an Eckart-like form only on highly symmetric backgrounds where the transverse contribution vanishes or collapses to a single gradient direction. We also make a brief comment on the existence of temperature gradients $D_a{T}_g$.

We study spherically symmetric, self-similar wormhole solutions supported by colliding streams of negative-energy null dust, and their dynamical formation. Under the assumption of self-similarity, the Einstein equations reduce to a system of ordinary differential equations, which we solve numerically under boundary conditions enforcing the existence of a minimal areal radius (the throat) on constant-time hypersurfaces. For a sufficiently large throat radius, the resulting geometries remain regular at both spatial and future null infinity, while a singularity is retained in the past direction. We then construct a dynamical formation scenario by patching together three regions: a Schwarzschild black hole, negative-energy Vaidya spacetimes, and the self-similar wormhole geometry. These regions are joined across null shells using the Barrabès-Israel formalism, which provides explicit relations among the throat radius, the black hole’s mass, and the energy injection by the shell, demonstrating that an initial black hole can evolve into a wormhole. Our analysis generalizes the formation model for static wormhole solutions proposed by Hayward and Koyama in 2004 to nonstatic wormhole solutions, offering a novel perspective on the formation of regular traversable wormholes.

We analyze the propagation and polarization properties of high-frequency gravitational waves in Einstein-Æther theory on vorticity-free and slowly varying backgrounds at both leading and next-to-leading orders within the geometric optics approximation. The linear perturbation analysis is performed in the background Æther-orthogonal frame, in which the axes of the gravitational wave sound cones remain perpendicular to these hypersurfaces, thereby simplifying the analysis. The leading-order results show that Einstein-Æther theory admits two tensor modes, two vector modes, and one scalar mode, consistent with the findings in the flat spacetime background. We further derive the dispersion relations and linear stability conditions for these modes in curved backgrounds. At next-to-leading order, we obtain the amplitude evolution equations, finding that the graviton number is conserved for the tensor modes but not for the vector and scalar modes. Next-to-leading-order effects also induce mixing among polarization modes. Our study demonstrates that, after imposing the GW170817 constraint on the propagation speed of gravitational waves, the vector modes mixed with the leading-order tensor modes cannot be used to distinguish between general relativity and Einstein-Æther theory. On the other hand, the mixing between scalar modes and the leading-order tensor modes leads to distinct predictions in the two theories, providing a promising avenue to test Einstein-Æther gravity through the detection of polarization mixing in gravitational waves.

The effective field theory (EFT) of dark energy provides a model-independent framework for studying cosmology within scalar-tensor theories. In this work, we explore how the time evolution of the cosmological background, inferred from cosmic chronometer measurements of the Hubble parameter, can be used to reconstruct the relevant EFT functions. Our approach enables the direct determination of these EFT functions from observational data without assuming any specific cosmological model. This makes it possible to test the background evolution of a wide range of dark energy models, including the $\mathrm{\Lambda }\mathrm{CDM}$ (cold dark matter) model. We further demonstrate how the reconstructed EFT functions can be applied to constrain concrete theories, such as the quintessence model.

Neutron stars (NSs) are interesting objects capable of reaching densities unattainable on Earth. The properties of matter under these conditions remain a mystery. Exotic matter, including quark matter, may be present in the NS core. In this work, we explore the possible compositions of NS cores, in particular, the possible existence of large quark cores. We use the relativistic mean-field (RMF) model with nonlinear terms for the hadron phase and the Nambu–Jona-Lasinio (NJL) model and mean-field theory of quantum chromodynamics (MFTQCD) for the quark phase. Through Bayesian inference, we obtain different sets of equations: four sets with hybrid equations and one set with only the hadron phase. We impose constraints regarding the properties of nuclear matter, x-ray observational data from NICER, gravitational wave data from the binary neutron star merger GW170817, perturbative QCD calculations, and causality. The MFTQCD allows for a phase transition to quark matter at low densities, just above saturation density, while for the NJL sets, the phase transition occurs above twice the saturation density. As a result, the MFTQCD model predicts the presence of quark matter in the inner core of $1.4M_{\odot }$ NSs, while NJL models suggest a low probability of quark matter in the interior of a $1.4M_{\odot }$ NS. Both models predict the existence of quark matter in $2M_{\odot }$ NSs. The slope of the mass-radius curve has been shown to carry information about the presence of quark matter. In particular, a positive slope at $1.8M_{\odot }$ indicates the presence of non-nucleonic matter. A hybrid star with a stiff quark equation of state could explain a larger radius in more massive stars, such as two solar mass stars, compared to canonical NSs.

$\gamma$-ray pulsar halos, most likely formed by inverse Compton scattering of electrons and positrons propagating in the pulsar-surrounding interstellar medium with background photons, serve as an ideal probe for Galactic cosmic-ray propagation on small scales (typically tens of parsecs). While the associated electron and positron propagation is often modeled using homogeneous and isotropic diffusion, termed here as standard diffusion, the actual transport process is expected to be more complex. This work introduces the Pulsar Halo Emission Computation Tool (phect), a lightweight software designed for modeling pulsar halo emission. phect incorporates multiple transport models extending beyond standard diffusion, accounting for different possible origins of pulsar halos. Users can conduct necessary computations simply by configuring a yaml file without manual code edits. Furthermore, the tool adopts finite-volume discretizations that remain stable on nonuniform grids and in the presence of discontinuous diffusion coefficients. phect is ready for the increasingly precise observational data and the rapidly growing sample of pulsar halos.

We study the properties of the neutron-star crust within a Bayesian framework based on a unified relativistic mean-field (RMF) description of dense matter. The analysis focuses on the posterior distributions of crust properties, constrained by nuclear experimental data, chiral effective field theory, and multimessenger neutron star observations. In the inference, the outer crust is fixed using the AME2020 nuclear mass table, supplemented by Hartree-Fock-Bogoliubov mass models, while the inner crust is described using a compressible liquid-drop model consistently coupled to the RMF interaction. The same RMF framework is used to describe the uniform core, ensuring a unified treatment across all density regimes. From the resulting posteriors, we extract key crustal observables, including the crust-core transition density and pressure, crust thickness, crust mass, and the fractional crustal moment of inertia. We find that the transition density is primarily governed by the symmetry-energy slope $L$ and curvature $K_{\mathrm{sym}}$ evaluated at subsaturation densities, while the transition pressure plays a central role in determining global crustal properties. The inner-crust equation of state reflects a collective interplay between isovector nuclear-matter properties rather than a dependence on any single parameter. We also assess the impact of using matched crust-core constructions and show that they can introduce systematic differences in predicted neutron star properties when compared with fully unified treatments.

This work investigates the use of linear Paul traps as quantum sensors for detecting megahertz gravitational waves. Single-ion configurations exploit graviton-photon conversion in the presence of external magnetic fields, while two-ion systems use relative-motion excitations, which do not require magnets, to distinguish gravitational waves from axion dark matter. Furthermore, we show that entanglement of $N$ vibrational qubits enhances the signal probability by a factor of $N^2$, improving sensitivity beyond the standard quantum limit.

At its lowest frequencies, LIGO is limited by noise in its many degrees of freedom of suspended optics, which, in turn, introduce noise in the interferometer through their feedback control systems. Nonlinear interactions are a dominant source of low-frequency noise, mixing noise from multiple degrees of freedom. The lowest-order form is bilinear noise, in which the noise from two feedback-controlled subsystems multiplies to mask gravitational waves. Bilinear couplings require control trade-offs that simultaneously balance high- and low-frequency noise. Currently, there is no known lower limit to bilinear control noise. Here, we develop benchmark cost functions for bilinear noise and associated figures of merit. Linear-quadratic-Gaussian (LQG) control then establishes aggressive feedback that saturates the lower bounds on the cost functions. We then develop a mixed LQG and ${\mathcal{H}}_{\infty }$ approach to directly compute stable, robust, and optimal feedback, using the LIGO’s alignment control system as an example. Direct computations are fast while ensuring a global optimum. By calculating optimal robust control, it is possible to construct the lower bound on control noise along the Pareto front of practical controllers for LIGO. This method can be used to drastically improve control noise in existing observatories as well as to set subsystem control noise requirements for next-generation detectors with parametrized design.

We firstly carry out a systematic analysis on the spin ${\frac{1}{2}}^{+}\to {\frac{3}{2}}^{+}$ weak transition process in the framework of three-point QCD sum rules, where the initial and final states are doubly and singly charmed baryons. On the phenomenological side, all possible couplings of interpolating current to hadronic states are considered. In doing operator production expansion on the QCD side, the contributions of the perturbative part and vacuum condensate terms of $⟨\overline{q}q⟩$, $⟨g_s^{2}GG⟩$, $⟨\overline{q}{g}_s\sigma Gq⟩$, and $g_s^2⟨\overline{q}q{⟩}^2$ are all considered. After the form factors in the spacelike region ($Q^2>0$) are obtained, the numerical results are extrapolated into the timelike region ($Q^2<0$) by a fitting function. Using the predicted form factors, we finally analyze the semileptonic decays of ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{*+}{l}^{+}{\nu }_l$, ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Xi }}_c^{\prime *+}{l}^{+}{\nu }_l$, ${\mathrm{\Omega }}_{cc}^{+}\to {\mathrm{\Xi }}_c^{\prime *0}{l}^{+}{\nu }_l$, and ${\mathrm{\Omega }}_{cc}^{+}\to {\mathrm{\Omega }}_c^{*0}{l}^{+}{\nu }_l$ with $l=e$, $\mu$. The predictions in this work can deepen our understanding of the dynamics in the decay processes of doubly heavy baryons and provide useful information to explore the possibility of new physics in heavy baryonic decay channels.

Precise neutrino energy reconstruction is essential for next-generation long-baseline oscillation experiments, yet current methods remain limited by large uncertainties in neutrino-nucleus interaction modeling. Even so, it is well established that different interaction channels produce systematically varying amounts of missing energy and therefore yield different reconstruction performance–information that standard calorimetric approaches do not exploit. We introduce a strategy that incorporates this structure by classifying events according to their underlying interaction type prior to energy reconstruction. Using supervised machine-learning techniques trained on labeled generator events, we leverage intrinsic kinematic differences among quasielastic scattering, meson-exchange current, resonance production, and deep-inelastic scattering processes. A cross-generator testing framework demonstrates that this classification approach is robust to microphysics mismodeling and, when applied to a simulated DUNE ${\nu }_{\mu }$ disappearance analysis, yields improved accuracy and sensitivity at the 10%–20% level. These results highlight a practical path toward reducing reconstruction-driven systematics in future oscillation measurements.

Single-field freeze-in dark matter barely leaves observable footprints in dark matter direct detection, collider, or fixed-target experiments, which can be altered in the two-field context. In this work, we consider sequential freeze-in dark matter through signals of a dark photon mediator with a mass range of $m_{A^{\prime }}\sim {10}^{-2}–10\mathrm{GeV}$ covered by the proposed SHiP experiment. We show that the dark charge is fixed to be $e^{\prime }\sim 1.3\times {10}^{-12}$ and the mixing parameter is restricted to ${10}^{-11}\le \epsilon <{10}^{-8}–{10}^{-7.5}$, as a result of the out-of-equilibrium condition of dark photon and the observed relic abundance of dark matter. Within this $\epsilon$ region, the 5-yr (15-yr) data of the proton bremsstrahlung process for the dark photon, assuming vector meson (dipole) dominance, excludes $\epsilon \ge {10}^{-8.5}({10}^{-7.9})$ at 90% confidence level, implying only a narrow region of $\epsilon$ close to $\sim {10}^{-11}$ left for alternative tests.

We propose a detector concept, LAYered CAvern Surface Tracker (LAYCAST), to be installed on the ceiling and the wall of the cavern hosting the main experiment of future electron-positron colliders such as CEPC and FCC-ee. With detailed and realistic considerations of the design of such a new experiment, the proposed detector is dedicated to extending the sensitivity reach of the main detector to various theoretical scenarios of long-lived particles (LLPs). We study carefully four such scenarios involving a light scalar boson $X$, the heavy neutral lepton $N$, the lightest neutralino ${\tilde{\chi }}_1^0$ in the R-parity-violating supersymmetry, and the axionlike particle $a$. Long-lived light scalar bosons are considered to be produced from the Standard Model (SM) Higgs boson’s decay ($h\to XX$) at the center-of-mass energy $\sqrt{s}=240\mathrm{GeV}$, while the other three types of LLPs are produced either from $Z$-boson decays (viz. $Z\to \nu N,{\tilde{\chi }}_1^0{\tilde{\chi }}_1^0$) or a direct scattering process ($e^{-}{e}^{+}\to \gamma a$) at $\sqrt{s}=91.2\mathrm{GeV}$, where $\gamma$ and $\nu$ denote the SM photon and neutrino, respectively. With Monte-Carlo simulations, we derive the sensitivities of the proposed experiment to these LLPs and the corresponding signal-event numbers. We also provide a dedicated estimate of a potentially important SM background from long-lived neutral kaons in hadronic $Z$ decays, and show that it is strongly suppressed by the combined requirements of the main detector and LAYCAST. Our findings show that LAYCAST can probe large new parameter space beyond both current bounds and the expected reach of the main experiments at CEPC and FCC-ee. Comparison with existing works in similar directions is also made.

We investigate the critical temperature of a relativistic Bose-Einstein condensate of charged bosons driven by rotation in a parallel magnetic field [Y. Liu and I. Zahed, Phys. Rev. Lett. 120, 032001 (2018)]. For noninteracting bosons, the critical temperature can only be determined for a system with fixed angular momentum. We find that the critical temperature of the noninteracting system vanishes due to the fact that the system is quasi-one-dimensional, indicating that noninteracting bosons cannot undergo Bose-Einstein condensation. For interacting bosons, we investigate a system with quartic self-interaction. We show that the order parameter vanishes and the off-diagonal long-range order is absent at any nonzero temperature because of the quasi-one-dimensional feature, in accordance with the Coleman-Mermin-Wagner-Hohenberg theorem.

Dense QCD matter can feature a moat regime, where the static energy of mesons is minimal at nonzero momentum. Valuable insights into this regime can be gained using low-energy models. This, however, requires a careful assessment of model artifacts. We therefore study the effects of renormalization and in-medium modifications of quark-meson interaction on the moat regime. To capture the main effects, we use a two-flavor quark-meson model at finite temperature and baryon density in the random phase approximation. We put forward a convenient renormalization scheme to account for the nontrivial momentum dependence of meson self-energies and discuss the role of renormalization conditions for renormalization group consistent results on the moat regime. In addition, we demonstrate and that its extent in the phase diagram critically depends on the interaction of quarks and mesons.

Jets produced in association with a $Z^0$ or $W^{\pm }$ boson in hadronic collisions are automatically polarized due to the parity violation of weak interaction, making these processes ideal for understanding the spin transfer from polarized partons to polarized hadrons. Furthermore, leveraging this feature, we can also employ the weak-boson-tagged process to study the quenching phenomenon of polarized jets, an aspect that has rarely been discussed in the literature. In this work, we compute the polarization of $\mathrm{\Lambda }$ hyperons in $pp$ collisions and investigate the nuclear modification due to the jet-medium interaction in $AA$ collisions. Our results highlight this process as a valuable probe of polarized parton hadronization, particularly the circularly polarized gluon hadronization, and of spin-dependent medium effects in the QGP.