We extend the formalism of asymmetric frames of reference for generalized parton distributions (GPDs) to the case of nonzero skewness, i.e., including longitudinal momentum transfer. The framework, based on Lorentz-invariant amplitudes and previously developed and numerically implemented for unpolarized, helicity and transversity GPDs at zero skewness, gives efficient access to a broad range of kinematics, making full mapping of GPDs from the lattice realistic. The general-skewness formalism is tested using lattice data with both transverse and longitudinal or only longitudinal momentum transfer, the latter being a special case with a reduced number of independent amplitudes. We extract the amplitudes in coordinate space and express the GPDs $H$ and $E$ in terms of these amplitudes. This is followed by reconstruction of quasidistributions and their matching to the light cone. We further identify and discuss the principal challenges for nonzero skewness GPDs.

We reexamine by numerical simulation the phase structure of the ($3+1$)-dimensional $SU(2)$ lattice gauge theory with gauge fields coupled to Higgs fields at finite temperature. Concretely, we explore two different order parameters, which are able to distinguish the three phases of the theory: (i) the Fredenhagen-Marcu operator used to discriminate between deconfinement and confinement/Higgs phases and (ii) the Greensite-Matsuyama overlap operator proposed recently to distinguish confinement and Higgs phases.

We calculate the amplitudes and branching fractions of ${\chi }_{cJ}(1P)$, $h_c(1P)$, $J/\psi (1S)$, and $\psi (2S)$ radiative decays in the framework of the covariant confined quark model. First, we explicitly show that all calculated amplitudes are gauge invariant. Next, we use experimental data for three decay channels $J/\psi \to {\eta }_c\gamma$, ${\chi }_{c0}\to J/\psi \gamma$, and $\psi (2S)\to {\chi }_{c0}\gamma$ to fit the model parameters including the charm quark mass and the meson size parameter. Finally, we use the obtained parameters to predict the branching fractions of the decays $h_c\to {\eta }_c\gamma$, ${\chi }_{c1(c2)}\to J/\psi \gamma$, and $\psi (2S)\to {\chi }_{c1(c2)}\gamma$. Our predictions agree well with experimental data.

We compute the 00 element of the spin density matrix, denoted as ${\rho }_{00}$ and called the spin alignment, up to the second order of the gradient expansion in local equilibrium by Zubarev’s approach. In the first order, we obtain ${\rho }_{00}=1/3$, meaning that the contributions from thermal vorticity and shear stress tensor are vanishing. The nonvanishing contributions to ${\rho }_{00}-1/3$ appear in the second order of gradients in the Belinfante and canonical cases. We also discuss the properties of the spin density matrix under the time reversal transformation. The effective transport coefficient for the spin alignment induced by the thermal shear stress tensor is T odd in the first order, implying that the first order effect is dissipative.

The COMPASS Collaboration recently reported the observation of strange-meson spectra in the reaction $K^{-}+p\to K^{-}{\pi }^{-}{\pi }^{+}+p$ and found $K_3$ and $K_4$ states, with masses of $2119\pm 13_{-12}^{+45}\mathrm{MeV}$ and $2210\pm 40_{-30}^{+80}\mathrm{MeV}$, respectively. This discovery has significantly renewed interest, prompting a detailed and systematic study of high-spin kaons. In this work, we analyze the mass spectrum and the Okubo-Zweig-Iizuka-allowed two-body strong decay properties of high-spin kaons having $J^P=3^{\pm },4^{\pm }$, and $5^{\pm }$ within the framework of the modified Godfrey-Isgur model and the ${}^3{P}_0$ model. Moreover, we identify critical decay channels, which may serve as useful guidance for future experimental studies.

Based on $12.0{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data samples collected by the BESIII detector at center-of-mass energies from 4.1271 to 4.3583 GeV, a partial wave analysis is performed for the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$. The cross sections for the subprocesses $e^{+}{e}^{-}\to {\pi }^{+}{Z}_c(3900{)}^{-}+\mathrm{c}.\mathrm{c}.\to {\pi }^{+}{\pi }^{-}J/\psi$, $f_0(980)(\to {\pi }^{+}{\pi }^{-})J/\psi$, and $({\pi }^{+}{\pi }^{-}{)}_{\mathrm{S}\text{−}\mathrm{wave}}J/\psi$ are measured for the first time. The mass and width of the $Z_c(3900{)}^{\pm }$ are determined to be $3884.6\pm 0.7\pm 3.3\mathrm{MeV}/c^2$ and $37.2\pm 1.3\pm 6.6\mathrm{MeV}$, respectively. The first errors are statistical and the second systematic. The final state $({\pi }^{+}{\pi }^{-}{)}_{\mathrm{S}\text{−}\mathrm{wave}}J/\psi$ dominates the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$. By analyzing the cross sections of ${\pi }^{\pm }{Z}_c(3900{)}^{\mp }$ and $f_0(980)J/\psi$, $Y(4220)$ has been observed. Its mass and width are determined to be $4225.7\pm 4.1\pm 3.4\mathrm{MeV}/c^2$ and $57.5\pm 9.4\pm 12.1\mathrm{MeV}$, respectively.

We present predictions for the zero-temperature equation of state at finite isospin density using the Nambu-Jona-Lasinio (NJL) model within the medium separation scheme (MSS)—a scheme that explicitly disentangles medium effects from the ultraviolet divergent vacuum terms. Recent lattice QCD results reveal a nonmonotonic speed of sound ($c_s^2$) as a function of isospin chemical potential (${\mu }_I$), exhibiting explicit violation of the conformal bound $c_s^2=1/3$. These findings have attracted significant theoretical interest, as established models—including the NJL model—failed to anticipate this behavior prior to lattice simulations. Conventional NJL implementations yield unphysical artifacts, often attributed to regularization scale sensitivity stemming from nonrenormalizability. However, in this work, we demonstrate that the standard NJL framework combined with MSS quantitatively reproduces state-of-the-art lattice data for isospin QCD.

Quasinormal modes and power-law late-time decay tails of a charged scalar field in a charged black hole background have been studied, but never in the fully nonlinear regime, as far as we know. In this paper, we study the dependence of these properties on the charges of scalar field and black hole. For the quasinormal modes, a fit of the spherical fundamental mode is shown for the purely uncharged case and compared to the charged one. We also see for the first time the transition from gravitational decay to pure electromagnetic decay, and show disagreement with the oscillation frequency between real and imaginary parts of the scalar field prescribed in the literature. Full nonlinear evolutions of hyperboloidal slices in spherical symmetry were used to obtain our results, allowing for the extraction of signals at future null infinity.

We investigate heat propagation in rigidly rotating bodies within the theory of general relativity. Using a first-order gradient expansion, we derive a universal partial differential equation governing the temperature evolution. This equation is hyperbolic, causal, and stable, and it naturally accounts for both rotational and gravitational Tolman-Ehrenfest effects. Any other first-order theory consistent with established physics (including the parabolic theories used in neutron star cooling models) must be equivalent to our formulation within an error that is of higher order in gradients. As a case study, we analyze heat transfer in solid cylinders rotating around their symmetry axis, so that the tangential speed approaches the speed of light on the surface. We also compute the relativistic rotational corrections to the cooling law of blackbodies.

Recent studies have shown that rotating black holes can undergo spontaneous scalarization, leading to deviations from general relativity (GR) in the strong-field regime. We present the first nonperturbative calculation of the quasinormal modes of scalarized Kerr black holes in Einstein-scalar-Gauss-Bonnet gravity, without assuming small spin or weak coupling. Our results reveal a universal splitting of the fundamental $l=m=2$ mode into axial-led, polar-led, and scalar-led branches, breaking the isospectrality characteristic of Kerr black holes. This splitting offers distinct signatures in the ringdown phase of gravitational wave signals and provides a new avenue to test gravity in the strong-field regime. Our findings open the possibility of probing beyond-GR physics using precision measurements of black hole ringdowns in upcoming gravitational wave observations.

We present a conceptually simple method for finding quasinormal modes (QNMs) in a Schwarzschild black hole. QNMs are defined by their boundary conditions at infinity and at the horizon. These include the intuitively satisfying assertion that the QNM should be purely outgoing at infinity, with no incoming wave coming from infinity and scattering off the black hole. One applies this condition at past null infinity by demanding that the incoming wave there vanish, despite the infinite outgoing wave at the same point in spacetime. We search for QNMs by minimizing the incoming wave, but we are forced to work at a finite distance rather than past null infinity, to avoid the infinite outgoing wave. This technique lets us find the fundamental QNM, but we do not succeed in finding the overtones since the incoming waves always vanish due to damping. The technique is inherently approximate due to the boundary condition at a finite distance.

We update constraints on a simple model of self-interacting neutrinos involving a heavy scalar mediator with universal flavor coupling. According to past literature, such a model is allowed by cosmic microwave background (CMB) data, with some CMB and large-scale structure data even favoring a strongly interacting neutrino ($\mathrm{SI}\nu$) scenario over $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$). In this work, we reevaluate the constraints on this model in light of the new Planck NPIPE data, DESI BAO data, and the effective field theory of large scale structures (EFTofLSS) applied to BOSS data. We find that Planck NPIPE are more permissive to the $\mathrm{SI}\nu$ scenario and that DESI data favor the $\mathrm{SI}\nu$ over $\mathrm{\Lambda }\mathrm{CDM}$. However, when considering EFTofBOSS data, this mode is no longer preferred. Therefore, new DESI data analyzed under the EFTofLSS are particularly awaited to shed light on this disagreement.

The 21-cm signals from cosmic dawn and the epoch of reionization contain valuable information on cosmological structure formation dominated by dark matter. Measurements of the 21-cm power spectrum can thus probe certain dark matter candidates. Here we investigate the impacts of fuzzy dark matter (FDM) on the 21-cm signals, taking into account both the linear matter power spectrum and the halo mass function (HMF) in FDM cosmologies. The full FDM dynamics are implemented in reionization simulations, along with a new ansatz on modulation of the FDM HMF by the linear overdensity. Not only does the suppression of FDM halos on small scales give rise to delay of the signature epochs during cosmic reionization, but these epochs are also shortened relative to the cold dark matter cosmology. In addition, we find that while the FDM effects on the 21-cm power spectrum are dominated by its linear dynamics early in cosmic dawn, a correct FDM HMF resulting from nonlinear wave dynamics must be considered when x-ray heating begins. We forecast the constraints on the FDM model parameters from upcoming 21-cm power spectrum measurements by SKA1-Low (central area). In FDM cosmologies with $m_{\mathrm{FDM}}={10}^{-21}\mathrm{eV}$, SKA1-Low will be able to constrain the boson mass to within $\sim 10\%$ at $2\sigma$ confidence with a mock 1080-hour observation, if the ionizing efficiency is mass independent. However, our results show that realistic astrophysical processes are degenerate with the FDM effects, which shall severely loosen the constraints on the boson mass from 21-cm power spectrum data alone.

In recent years, the interaction between dark matter (DM) and dark energy (DE) has become a topic of interest in cosmology. Interacting dark matter dark energy (IDE) models have a substantial impact on the formation of cosmological large-scale structures, which serve as the environment for DM halo evolution. This impact can be examined through the shape and spin orientation of halos in numerical simulations incorporating IDE effects. In our work, we used the N-body simulation pipeline me-gadget to simulate and study the halo spin and orientation in IDE models. We found that, in models where DM transfers into DE (IDE I), the alignment of halo shapes with the surrounding tidal field is enhanced compared to $\mathrm{\Lambda }\mathrm{CDM}$, while the alignment of halo spins with the tidal field is decreased compared to the $\mathrm{\Lambda }\mathrm{CDM}$. Conversely, in models where DE transfers into DM (IDE II), the opposite occurs. We have provided fitted functions to describe these alignment signals. Our study provides the foundation for more accurate modeling of observations in future surveys such as China Space Station Telescope.

We present the mass-spin diagram for classifying black holes and studying their formation pathways providing an analog to the Hertzsprung-Russell diagram. This allows for black hole evolutionary tracks as a function of redshift, combining formation, accretion, and merger histories for the variety of black hole populations. A realistic black hole continuum constructed from initial mass and spin functions and approximate redshift evolution reveals possible black hole main sequences, such as sustained coherent accretion through cosmic time or hierarchical merger trees. In the stellar-mass regime, we use a binary population synthesis software to compare three spin prescriptions for tidal evolution of Wolf-Rayet progenitors, showing how the mass-spin diagram exposes interesting modeling differences. We then classify black hole populations by applying supervised and unsupervised machine learning clustering methods to mass-spin datasets. While bare unsupervised clustering can nearly recover canonical population boundaries (stellar-mass, intermediate-mass, and supermassive), a more sophisticated approach utilizing deep learning via variational autoencoders for latent space representation learning aids in clustering of realistic datasets with subclasses that highly overlap in mass-spin space. We find that a supervised random forest can accurately recover the correct clusters from the learned latent space representation depending on the complexity of the underlying dataset, semisupervised methods show potential for further development, and the performance of unsupervised classifiers is a great challenge. Our findings motivate future machine learning applications and demonstrate that the mass-spin diagram can be used to connect gravitational-wave and electromagnetic observations with theoretical models.

We report new constraints on the velocity-independent annihilation cross section $⟨\sigma v⟩$ of keV-scale dark matter particles based on 11 years of observations with the Nuclear Spectroscopic Telescope Array (NuSTAR) x-ray observatory. Using the unfocused stray light mode of the instrument, which provides a wide field-of-view and a stable instrumental background, we perform a sensitive search for photon signatures from dark matter annihilation in the Galactic halo. We model the resulting diffuse x-ray spectrum over the 3–20 keV energy range and search for linelike spectral features that may arise from the annihilation of dark matter particles into photons. No statistically significant excess over the expected astrophysical background is found. We therefore place upper limits on $⟨\sigma v⟩$ as a function of dark matter mass, assuming a velocity-independent s-wave annihilation and several Galactic dark matter profiles. Across most of the explored mass range our results provide the strongest x-ray constraints to date, reaching the level of $⟨\sigma v⟩\lesssim {10}^{-33}-{10}^{-34}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$, and they complement the most recent estimates obtained from observations of the ART-XC telescope of the Spektr-RG observatory.

Quasinormal mode (QNM) spectra of black holes exhibit two open problems [Conf. Proc. C 0405132, 145 (2004); Classical Quantum Gravity 26, 163001 (2009) ]: (i) the discontinuity in highly damped QNMs between Schwarzschild and Kerr solutions as $a\to 0$, and (ii) the unexplained spectral proximity between QNMs and algebraically special (AS) frequencies, particularly the anomalous multiplet splitting for Kerr $\ell =2$, $m\ge 0$ modes. We develop a novel method to compute complete QNM spectra for type-D black holes, solving both problems and establishing a mathematical framework for boundary value problems of dissipative systems. Using analytic continuation of radial eigenvalue equations, our method eliminates the dependence on auxiliary parameters in the connection formulas for confluent Heun solutions. This breakthrough overcomes the longstanding challenge of calculating QNMs that cross or lie on the negative imaginary axis (NIA). For Schwarzschild and Kerr spacetimes ($0\le n\le 41$, $2\le \ell \le 16$), we present complete spectra validated through scattering amplitudes with errors $<{10}^{-10}$. The results provide definitive solutions to both open problems: (i) The inability of conventional methods to compute QNMs crossing or residing on the NIA leads to apparent discontinuities in Kerr spectra as $a\to 0$. (ii) When a QNM exactly coincides with the AS frequency, an additional QNM (unconventional mode) appears nearby. For the Kerr case with $\ell =2$, overtone sequences from both unconventional and AS modes exhibit precisely $2\ell +1$ branches, without multiplets or supersymmetry breaking at AS frequencies. Our method confirms Leung’s conjecture of high-$\ell$ unconventional mode deviations from the NIA through the first $\ell =3$ calculation. Moreover, this paradigm surpasses the state-of-the-art Cook’s continued fraction and isomonodromic methods in computational efficiency.

Minimizing coating thermal noise is crucial for enhancing gravitational wave detector sensitivity, with a target amplitude spectral density reduction factor (henceforth ASD RF) of 0.5 relative to the coatings used currently. This study investigates the design of low-noise dielectric stacks using the double stack of doublets strategy, explored via ad hoc optimization heuristics specifically developed for efficient parametric analysis of coating performance. We analyze the performance limits of ternary coatings based on ${\mathrm{SiO}}_2$, $\mathrm{Ti}\colon\colon {\text{SiO}}_2$, and $\mathrm{Ti}\colon\colon {\text{GeO}}_2$, considering both their material and optical properties with respect to detector constraints. Optimization results suggest such coating configurations, even with a relaxed absorbance constraint (1 ppm), fall short of the target, achieving a best ASD RF of $\sim 0.69$. Consequently, we explore alternative ternary double stack of doublets designs incorporating higher refractive index materials. Simulations demonstrate that incorporating alternative high-index materials offers a promising pathway, potentially enabling the achievement of the project target. We discuss the optimization strategies, performance trade-offs, design robustness, and implications of using high-index, potentially higher-loss materials for next-generation optical coatings.

We present a search for short-duration gravitational-wave transients in data from the first eight months of Advanced LIGO-Virgo-KAGRA’s fourth observing run, denoted O4a. We use four analyses which are sensitive to a wide range of potential signals lasting up to a few seconds in the 16–4096 Hz band. Excluding binary black hole merger candidates that were already identified by low-latency analyses, we find no statistically significant evidence for other gravitational-wave transients. We measure the sensitivity of the search for representative signals, including sine-Gaussians, Gaussian pulses, and white-noise bursts with different frequencies and durations, adopting a false alarm rate of 1 per 100 years as detection threshold. Depending on signal type, we find improvements over previous searches by factors of 2 to 10 in terms of sensitivity to strain amplitude and of 90% confidence upper limit on the rate density of sources. We also evaluate a variety of core-collapse supernova models and find that, for some models, the search could have detected gravitational waves from stellar core-collapse throughout the Milky Way. Finally, we consider neutron star $f$-modes associated with pulsar glitches and find that, assuming a source similar to the Vela Pulsar, the search could have detected a gravitational-wave signal from a glitch with fractional frequency change as small as $\sim 2$ to $6\times {10}^{-5}$ depending on the neutron star mass.

The intrinsic fluctuations, memory effects, and long-range color interactions in high-energy nuclear collisions imply the presence of non-Markovian processes in the fireball evolution, which affects the thermalization process toward equilibrium and produces a nonextensive behavior. In order to investigate the nonequilibrium effect on the quantum chromodynamics (QCD) phase transition at finite temperature ($T$) and chemical potential ($\mu$), we apply a nonextensive correction to the equation of state in the parton (hadron resonance) gas at high (low) temperature and interpolate these two equations of state with a smooth crossover. The nonextensive statistics is characterized by a nonextensivity parameter $q$, which measures the degrees of deviation from the thermal equilibrium. It is found that the dimensionless thermodynamic quantities such as the entropy density, the pressure, the energy density, the specific heat at constant volume, and the trace anomaly are sensitive to the deviation of $q$ from unity, and they become large in both the hadronic and quark-gluon plasma phases with the increase of $q$. Moreover, this deviation leads to nontrivial corrections of the squared speed of sound [$(c_s^2{)}_q$] in the vicinity of the critical point ($T_c$) and at lower temperatures. Additionally, these thermodynamic quantities are sensitive to the deviation of $\mu$ from zero. With increasing $\mu$, they become enhanced in both phases. Specifically, for $(c_s^2{)}_q$, the value increases near $T_c$ but decreases at lower temperatures. Finally, we observe that our results with $q=1$ agree well with those from lattice QCD, the hadron resonance gas model, and the thermal-fist fit to the hadron yields in high-energy nuclear collisions in the low-temperature region up to $T\sim 150\mathrm{MeV}$.