We investigate the possibility of electromagnetic fields leaving imprints on gravitational wave signals from neutron star-black hole mergers, specifically in the context of extreme mass ratio inspirals. Using black hole perturbation theory in the context of a minimally coupled Einstein-Maxwell system on a Schwarzschild background, we demonstrate that electromagnetic quasinormal modes (QNMs) can excite gravitational QNMs with frequencies that are linear or quadratic in the electromagnetic QNMs, at the first level of mixing. Moreover, we then study the electromagnetism-gravity coupling by approximating the Regge-Wheeler and Zerilli potentials with Dirac delta functions. In this example, we examine gravitational perturbations induced by the electromagnetic field of an ideal dipole radially free falling toward the black hole, building on calculations from a companion paper [F. Aly and D. Stojkovic, Phys. Rev. D 111, 104083 (2025)]. Our results show that both linear and quadratic electromagnetic QNMs appear in gravitational perturbations. In addition, linear gravitational QNMs are also excited due to the electromagnetic source, with their amplitudes depending on the details of the electromagnetic and gravitational potentials, analogous to gravitational mode mixing analysis. Furthermore, at late stages, gravitational perturbations might exhibit polynomial tails induced by electromagnetic perturbations. This article sets the stage for future numerical investigations aimed at identifying such modes in various scenarios.

We investigate the fully relativistic spherical collapse model of a uniform distribution of mass $M$ with initial comoving radius ${\chi }_{*}$ and spatial curvature $k\equiv 1/{\chi }_k^2\le 1/{\chi }_{*}^2$ representing an overdensity or bounded perturbation within a larger background. Our model incorporates a perfect fluid with an evolving equation of state, $P=P(\rho )$, which asymptotically transitions from pressureless dust ($P=0$) to a ground state characterized by a uniform, time-independent energy density ${\rho }_{\mathrm{G}}$. This transition is motivated by the quantum exclusion principle, which prevents singular collapse, as observed in supernova core-collapse explosions. We analytically demonstrate that this transition induces a gravitational bounce at a radius $R_{\mathrm{B}}=(8\pi G{\rho }_{\mathrm{G}}/3{)}^{-1/2}$. The bounce leads to an exponential expansion phase, where $P(\rho )$ behaves effectively as an inflation potential. This model provides novel insights into black hole interiors and, when extended to a cosmological setting, predicts a small but nonzero closed spatial curvature: $-0.07\pm 0.02\le {\mathrm{\Omega }}_k<0$. This lower bound follows from the requirement of ${\chi }_k\ge {\chi }_{*}\simeq 15.9\mathrm{Gpc}$ to address the cosmic microwave background low quadrupole anomaly. The bounce remains confined within the initial gravitational radius $r_{\mathrm{S}}=2GM$, which effectively acts as a cosmological constant $\mathrm{\Lambda }$ inside $r_{\mathrm{S}}=\sqrt{3/\mathrm{\Lambda }}$ while still appearing as a Schwarzschild black hole from an external perspective. This framework unifies the origin of inflation and dark energy, with its key observational signature being the presence of small but nonzero spatial curvature, a testable prediction for upcoming cosmological surveys.

Extreme mass-ratio inspirals (EMRIs) are key observational targets for the Laser Interferometer Space Antenna (LISA) mission. Unresolvable EMRI signals contribute to the formation of a gravitational wave background (GWB). Characterizing the statistical features of the GWB from EMRIs is of great importance, as EMRIs will ubiquitously affect large segments of the inference scheme. In this work, we apply a frequentist test for GWB Gaussianity and stationarity, exploring three astrophysically motivated EMRI populations. We construct the resulting signal by combining state-of-the-art EMRI waveforms and a detailed description of the LISA response with time-delay interferometric variables. Depending on the brightness of the GWB, our analysis demonstrates that the resultant EMRI foregrounds show varying degrees of departure from the usual statistical assumptions that the GWBs are both Gaussian and stationary. If the GWB is nonstationary with non-Gaussian features, this will challenge the robustness of the Gaussian-likelihood model, when applied to global inference results, e.g., foreground estimation, background detection, and individual-source parameter reconstruction.

We derive an analytic form of the joint prior of effective spin parameters, ${\chi }_{\mathrm{eff}}$ and ${\chi }_{\mathrm{p}}$, assuming an isotropic and uniform-in-magnitude spin distribution. This is a vital factor in performing hierarchical Bayesian inference for studying the population properties of merging compact binaries observed with gravitational waves. In previous analyses, this was evaluated numerically using kernel density estimation (KDE). However, we find that this numerical approach is inaccurate in certain parameter regions, where both $|{\chi }_{\mathrm{eff}}|$ and ${\chi }_{\mathrm{p}}$ are small. Our analytic approach provides accurate computations of the joint prior across the entire parameter space and enables more reliable population inference. Employing our analytic prior, we reanalyze binary black holes in the gravitational-wave transient catalog 3 (GWTC-3) by the LIGO-Virgo-KAGRA collaboration. While the results are largely unchanged, log-likelihood errors due to the use of the inaccurate prior evaluations are $\mathcal{O}(1)$, implying the bias is already at the concerning level if one adopts a log-likelihood variance cut. Since the systematic bias from the numerical method accumulates with the increasing number of events, our analytic prior will be more crucial in future analyses.

In this paper we proposed the homotopy approach for solving the nonlinear Balitsky-Kovchegov evolution equation with running QCD coupling. The approach consists of two steps. First, is the analytic solution to the nonlinear evolution equation for the simplified, leading twist kernel. Second, is the iteration procedure that allow us to calculate corrections analytically or seminumerically. For the leading twist kernel it is shown that the first iteration leads to $\le 1\%$ accuracy. The $\zeta =-\frac{4N_c}{b_0}Y\ln ({\overline{\alpha }}_S(1/Q_s^2(Y))/{\overline{\alpha }}_S(r^2))$ ($r$ is the dipole size, $Q_s$ is the saturation scale) and geometric scaling behavior of the scattering amplitude are discussed as well as the dependence on the value of the infrared cutoff.

In this paper, we systematically investigate the general spin-1 dark matter–nucleus interactions within the framework of effective field theories (EFTs). We consider both the nonrelativistic (NR) and the relativistic EFT descriptions of the DM interactions with nucleons and quarks. In the NREFT framework, we present a complete list of NR operators for spin-1 DM coupling to nucleons and compute their contributions to the DM response functions. Next, we consider all possible leading-order relativistic EFT operators between DM and light quarks and the photon, and we perform NR reductions to match them onto the NREFT. We then derive the nuclear scattering rate from these interactions and employ recent DM direct detection data (from both the nuclear recoil and the Migdal effect) to constrain all these EFT operators and DM electromagnetic properties. We find that the elastic nuclear recoil data (from PandaX-4T, XENONnT, LZ, and DarkSide-50) set stringent bounds on the EFT coefficients for a DM mass above a few GeV, while the Migdal-effect datasets (from PandaX-4T, XENONnT, and DarkSide-50) can probe a DM mass region as small as 20 MeV. Lastly, we construct a UV-complete model that can provide a complex spin-1 DM candidate, and at the same time generate DM-quark/photon operators discussed in this work.

There is strong evidence supporting center vortices as underpinning confinement and dynamical chiral symmetry breaking—the two key features of nonperturbative QCD. In our recent paper [1] we find that dynamical mass generation vanishes upon vortex removal in full QCD with a near-physical quark mass. In this work we extend those results and consider the influence of center vortex removal on the overlap Landau-gauge quark propagator at multiple valence quark masses on the same dynamical QCD ensemble, keeping fixed the near-physical sea quark mass. After carefully applying a smoothing process we also find that dynamical mass generation is reproduced on the corresponding vortex-only fields. This vortex-only dynamical mass shows qualitative agreement with the untouched Monte Carlo gauge field results. The results reported herein lend further credence to the important relationship between dynamical fermions and center vortices and the mediation of nonperturbative phenomena in QCD.

We present updated results for the wave function normalization constants and the first moments of the light-cone distribution amplitudes for the lowest-lying baryon octet. The analysis is carried out on a large number of $n_f=2+1$ lattice gauge ensembles, including ensembles at physical pion (and kaon) masses. These are spread across five different lattice spacings, enabling a controlled continuum limit. The main differences with respect to our earlier work [G. S. Bali et al. (RQCD Collaboration), Light-cone distribution amplitudes of octet baryons from lattice QCD, Eur. Phys. J. A 55, 116 (2019).] are the use of two-loop conversion factors to an $\overline{\mathrm{MS}}$-like scheme and of an updated set of low-energy constants in the parametrization of the quark mass dependence. As a byproduct, for the first time, the anomalous dimensions for local leading-twist three-quark operators with one derivative are obtained.

Resonant anomaly detection methods have great potential for enhancing the sensitivity of traditional bump hunt searches. A key component of these methods is a high quality background template used to produce an anomaly score. Using the LHC Olympics R&D dataset, we demonstrate that this background template can also be repurposed to directly estimate the background expectation in a simple cut and count setup. In contrast to a traditional bump hunt, no fit to the invariant mass distribution is needed, thereby avoiding the potential problem of background sculpting. Furthermore, direct background estimation allows working with large background rejection rates, where resonant anomaly detection methods typically show their greatest improvement in significance.

We demonstrate transfer learning capabilities in a machine-learned algorithm trained for particle-flow reconstruction in high energy particle colliders. This paper presents a cross-detector fine-tuning study, where we initially pretrain the model on a large full simulation dataset from one detector design, and subsequently fine-tune the model on a sample with a different collider and detector design. Specifically, we use the Compact Linear Collider detector (CLICdet) model for the initial training set and demonstrate successful knowledge transfer to the CLIC-like detector (CLD) proposed for the Future Circular Collider in electron-positron mode. We show that with an order of magnitude less samples from the second dataset, we can achieve the same performance as a costly training from scratch, across particle-level and event-level performance metrics, including jet and missing transverse momentum resolution. Furthermore, we find that the fine-tuned model achieves comparable performance to the traditional rule-based particle-flow approach on event-level metrics after training on 100,000 CLD events, whereas a model trained from scratch requires at least 1 million CLD events to achieve similar reconstruction performance. To our knowledge, this represents the first full-simulation cross-detector transfer learning study for particle-flow reconstruction. These findings offer valuable insights towards building large foundation models that can be fine-tuned across different detector designs and geometries, helping to accelerate the development cycle for new detectors and opening the door to rapid detector design and optimization using machine learning.

Isospin asymmetric nuclear matter is introduced to V-QCD, a bottom-up holographic QCD model. Using a small isospin chemical potential, we extract the symmetry energy in the model, finding excellent agreement with experimental results for some of the potentials. Extending the calculation for finite- and arbitrary-sized isospin chemical potentials, we construct $\beta$-equilibrated neutron stars via the usual Tolman-Oppenheimer-Volkov equations. We find, pleasingly, that the neutron stars passing the mass-radius and tidal deformability constraints are those with the potentials that also lead to excellent symmetry energies.

Nontrivial conformal field theories are rare. Motivated by the recent construction of a local higher-spin gravity in ${\mathrm{AdS}}_4$—chiral higher-spin gravity—we begin to identify its anti–de Sitter/conformal field theory (AdS/CFT) dual theory that has to be a closed subsector of Chern-Simons matter theories, thereby shedding more light on this class of CFTs and the dualities that relate them. We show that at the level of two- and three-point functions the sub-CFT can be defined as a limit of Chern-Simons matter theories where only correlators with the total positive (or negative) helicity are kept. We also discuss extension to higher orders and list a number of nontrivial predictions from the bulk.

We argue that the Ising model conformal field theory (CFT) can be used to obtain some clear insights into three-dimensional (3D) (quantum) gravity with matter. We review arguments for the existence of its holographic description, and concentrate on the time dependence of perturbations of the theory at high temperature, which would correspond to throwing matter into a black hole in the dual picture. Apart from an expected quasi-normal-mode-like exponential damping, we observe a plateau, a burst, and a subsequent reemergence of the whole signal, the latter being apparently at odds with a black hole interpretation. We provide an explanation of this phenomenon in terms of the properties of bulk matter fields interacting with the Banados-Teitelboim-Zanelli black hole and the fact that the geometry/metric is not fundamental but a derived quantity in the Chern-Simons formulation of 3D gravity. This allows for evading the black hole information paradox in the present context.

The detection and subsequent inference of binary black hole signals rely heavily on the accuracy of the waveform model employed. In the highly nonlinear, dynamic, and strong-field regime near merger, these waveforms can only be accurately modeled through numerical relativity simulations. Considering the precision requirements of next-generation gravitational wave observatories, we present in this paper high-resolution simulations of four nonspinning quasicircular binary black hole systems with mass ratios of 1, 2, 3, and 4, conducted using the gr-athena++ code. We extract waveforms from these simulations using both finite radius and Cauchy characteristic extraction (CCE) methods. Additionally, we provide a comprehensive error analysis to evaluate the accuracy and convergence of the waveforms. Our self-mismatch study shows that the (2, 2) mode of the CCE strains, for the world tube extraction radius of $R=50$, reaches the level of $\sim {10}^{-12}$ mismatch for mass ratios of 1, 2, 3, and $\sim {10}^{-11}$ mismatch for the mass ratio of 4. However, when larger extraction radii are considered or when more modes are included the mismatches increase. These results highlight both the promise and limitations of current simulations in achieving the precision required for upcoming detectors such as Laser Interferometer Space Antenna, Cosmic Explorer, and Einstein Telescope.

We constrain the evolution of dark matter energy density over time, specifically focusing on deviation from the standard model represented by the equation ${\rho }_m\propto (1+z{)}^{3-ϵ}$, where $ϵ$ is a constant parameter. Utilizing a diverse array of observational datasets, including baryon acoustic oscillations (BAO) data from the first release of the Dark Energy Spectroscopic Instrument (DESI), distance priors derived from cosmic microwave background observations by the Planck satellite, Hubble rate data obtained through the cosmic chronometers method, type Ia supernova data from the Panthon sample, and the data from the redshift space distortion measurements ($f{\sigma }_8$), we derive stringent constraints on the deviation parameter. We find that for the model under consideration, the deviation parameter is constrained to be $ϵ=-0.0073_{-0.0033}^{+0.0029}$, indicating a deviation of approximately $2.4\sigma$ from the scenario where dark matter and vacuum dark energy do not interact. When compared with previous studies and alternative analyses, our findings provide corroborative evidence for an interaction between dark matter and vacuum dark energy, particularly in light of the release of BAO data from DESI.

We study the nonleptonic puzzle of $B_{d(s)}\to K^{(*)}{\overline{K}}^{(*)}$ decay in the $R$-parity violating minimal supersymmetric standard model extended with the inverse seesaw mechanism. In this model, the chiral flip of sneutrinos can contribute to the observables $L_{K\overline{K}}$ and $L_{K^{*}{\overline{K}}^{*}}$, that is beneficial for explaining the relevant puzzle. We also find that this unique effect can engage in the $B_s\text{−}{\overline{B}}_s$ mixing. We utilize the scenario of complex ${\lambda }^{\prime }$ couplings to fulfill the recent stringent constraint of $B_s\text{−}{\overline{B}}_s$ mixing, and examine other related bounds of $B$, $K$-meson decays, lepton decays, neutrino data, $Z$ decays, oblique parameters, $CP$ violations, etc. Besides, inspired by the new measurement of $\mathcal{B}(B^{+}\to K^{+}\nu \overline{\nu })$ by Belle II, which shows about $2.7\sigma$ higher than the Standard Model prediction, we also investigate the New Physics enhancement to this observable.

Prompted by several potential tetraquark states that have been reported by the LHCb, CMS, and ATLAS Collaborations in the di-$J/\mathrm{\Psi }$ and $J/\mathrm{\Psi }\mathrm{\Psi }(2S)$ spectra, we investigate their contribution to two-photon processes. Within a nonrelativistic potential model for the all-charm tetraquark states, we calculate the two-photon decay widths of these states and test model-independent sum rule predictions. Imposing such sum-rule constraints allows us to predict the light-by-light scattering cross sections in a consistent way and check if any excess, in comparison to the Standard Model prediction, as reported by ongoing ATLAS experiments, can be attributed to intermediate exotic states.

We confirm for the first time the existence of distinctive halo bias associated with the quadrupolar type of statistical anisotropy (SA) of the linear matter density field using cosmological $N$-body simulations. We find that the coefficient of the SA-induced bias for cluster-sized halos takes negative values and exhibits a decreasing trend with increasing halo mass. This results in the quadrupole halo power spectra in a statistically anisotropic universe being less amplified compared to the monopole spectra. The anisotropic feature in halo bias that we found presents a promising new tool for testing the hypothesis of a statistically anisotropic universe, with significant implications for the precise verification of anisotropic inflation scenarios and vector dark matter and dark energy models.