Motivated by recent efforts to bridge between weak- and strong-field descriptions of black-hole binary dynamics, we develop a resummation scheme for post-Minkowskian radiative observables in extreme-mass-ratio scattering, augmented with post-Newtonian terms. Specifically, we derive universal interpolation formulas for the total energy emitted in gravitational waves out to infinity and down the event horizon of the large black hole, valid to leading order in the small mass ratio. We test our formulas using numerical results from direct calculations in black hole perturbation theory. The central idea of our approach is to utilize as a strong-field diagnostic the known form of divergence in the radiated energy along geodesics near the parameter-space separatrix between scattering and plunge. The dominant, logarithmic term of this divergence can be expressed in terms of instantaneous energy fluxes calculated along the unstable circular geodesics that form the separatrix, fluxes that we obtain using interpolation of highly accurate numerical data. The same idea could be applied to bound-orbit radiative observables via either unbound-to-bound mapping or a direct resummation of bound-orbit post-Newtonian expressions.

Gravitational-wave (GW) standard sirens have the potential to measure the Hubble constant $H_0$ in the local Universe independent of the distance ladder and thus offer unique insights into the Hubble tension. A key challenge with standard sirens is detecting their electromagnetic counterparts and therefore assigning redshifts to the measured distances. One promising way to proceed is to utilize GW dark sirens—events without an identified electromagnetic counterpart—and cross-correlate their angular distribution with that of galaxies. We present a quantitative study of how precisely the Hubble constant can be measured using tomographic cross-correlation between galaxies and GW sources. Overall, we find that the constraints on $H_0$ will be limited by the quality and quantity of GW data. We find that percent-level constraints on $H_0$ will primarily depend on achieving small distance uncertainties (${\sigma }_{d_L}=0.1d_L$), obtaining a large number of GW dark sirens ($\gtrsim 5000$) and accurate sky localization in the tomographic analysis.

Combined measurements of baryon acoustic oscillations (BAOs) from the Dark Energy Spectroscopic Survey (DESI), the cosmic microwave background (CMB), and type Ia supernovae (SNe Ia) have recently challenged the $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) paradigm, indicating potential evidence for a dynamical dark energy component. These results are usually obtained in the context of the dark energy equation-of-state (EOS) parametrizations, generally implying in phantom crossing at intermediate redshifts. However, a general mapping between these parametrizations that yields approximately the same background observables clouds the inference of the true nature of dark energy in the context of these parametric methods. In this work, we propose a model-independent reconstruction of the dark energy density, which is more directly constrained than its EOS, based on the Gaussian process (GP) regression method with the use of DESI Data Release 2 BAO and compressed CMB data along with the Pantheon+, Union3, and Dark Energy Survey Supernova Year-5 (DESY5) SNe Ia samples. In addition, we perform a statistical comparison between the energy densities of $\mathrm{\Lambda }$, a nonphantom thawing quintessence-type dark energy, and the Chevallier-Polarski-Linder parametrization with the reconstructed function. We find that all models agree with the GP reconstruction at 95% confidence level, with the largest discrepancy coming from $\mathrm{\Lambda }\mathrm{CDM}$ with DESY5 at low redshifts. Even in this case, our findings suggest that it may be premature to claim statistically significant evidence for evolving or phantom dark energy with current DESI and SNe Ia measurements.

The combination of galaxy clustering and weak lensing is a powerful probe of the cosmology model. We present a joint analysis of galaxy clustering and weak lensing cosmology using Sloan Digital Sky Survey (SDSS) data as the tracer of dark matter (lens sample) and the Hyper Suprime-Cam year-3 (HSC Y3) dataset as source galaxies. The analysis divides HSC Y3 galaxies into four tomographic bins for both galaxy-galaxy lensing and cosmic shear measurements and employs a point-mass correction model to utilize galaxy-galaxy lensing signals down to $2h^{-1}\mathrm{Mpc}$, extending up to $70h^{-1}\mathrm{Mpc}$. These strategies enhance the signal-to-noise ratio of the galaxy-galaxy lensing data vector. Using a flat $\mathrm{\Lambda }\mathrm{CDM}$ model, we find $S_8=0.780_{-0.030}^{+0.029}$, and using a $w\mathrm{CDM}$ model, we obtain $S_8=0.756_{-0.036}^{+0.038}$ with $w=-1.176_{-0.346}^{+0.310}$. We apply uninformative priors on the redshift mean-shift parameters for the third and fourth tomographic bins. Leveraging the self-calibration power of tomographic weak lensing, we measure $\mathrm{\Delta }{z}_3=-0.112_{-0.049}^{+0.046}$ and $\mathrm{\Delta }{z}_4=-0.185_{-0.081}^{+0.071}$, in agreement with previous HSC Y3 results. This demonstrates that weak lensing self-calibration can achieve redshift constraints comparable to other methods such as photometric and clustering redshift calibration.

The combination of galaxy-galaxy weak lensing and galaxy clustering is a powerful probe of the cosmological model, and exploration of how to best model and extract this information from the signals is essential. We present the measurement of the galaxy-galaxy weak lensing signals using the SDSS DR11 spectroscopic galaxies as lens galaxies, and the HSC Y3 shear catalog as source galaxies, binned into four tomographic bins by their photometric redshift. The SDSS DR11 galaxies, with a redshift range $0.15<z<0.7$, are binned into three redshift bins, each as a probe for measuring the projected correlation function, $w_p(R_p)$. We measure the galaxy-galaxy lensing signal $\mathrm{\Delta }\mathrm{\Sigma }(R_p)$ in 12 lens-source bin pairs and show that there is no evidence for significant systematic biases in the measurement with null testing. We combine our $w_p(R_p)$ and $\mathrm{\Delta }\mathrm{\Sigma }(R_p)$ ($2\times 2\mathrm{pt}$) data vectors and perform likelihood inference with a flat $\mathrm{\Lambda }\mathrm{CDM}$ model. For $\mathrm{\Delta }\mathrm{\Sigma }(R_p)$, we extend the lower limit of the scale cut compared to previous HSC Y3 analyses to $2h^{-1}\mathrm{Mpc}$ by including a point-mass correction term in addition to the minimal bias model. We present various tests to validate our model and provide extended consistency tests. In the $\mathrm{\Lambda }\mathrm{CDM}$ context, our fiducial model yields $S_8=0.804_{-0.051}^{+0.051}$. The $2\times 2\mathrm{pt}$ data vector provides redshift parameter constraints for the third and fourth redshift bins $\mathrm{\Delta }{z}_3=-0.079_{-0.084}^{+0.074}$, and $\mathrm{\Delta }{z}_4=-0.203_{-0.206}^{+0.167}$, which is consistent with results from the previous tomographic cosmic shear studies, and serves as the foundation for a future $3\times 2\mathrm{pt}$ analysis.

Dark matter around black holes can induce drag forces through dynamical friction and accretion, potentially affecting the orbital evolution and gravitational wave emission of binary systems. We here present a series of two-dimensional general relativistic simulations of a black hole binary in a wind tunnel for an asymptotically homogeneous scalar field background. We extract the drag forces, torque, mass and charge accretion acting on the binary, and analyze their dependence on the binary separation, velocity and the scalar field parameters. We find that the binary’s drag is not a simple superposition of two isolated black holes; the presence of a companion modifies the gravitational wake and yields significant nonlinearities. This additional force and torque can (in principle) modify the inspiral and induce a dephasing of the gravitational wave signal.

With pulsar timing arrays (PTAs) having observed a gravitational wave background (GWB) at nanohertz frequencies, the focus of the field is shifting toward determining and characterizing its origin. While the primary candidate is a population of GW-emitting supermassive black hole binaries (SMBHBs), many other cosmological processes could produce a GWB with similar spectral properties as have been measured. One key argument to help differentiate an SMBHB GWB from a cosmologically sourced one is its level of anisotropy; a GWB sourced by a finite population will likely exhibit greater anisotropy than a cosmological GWB through finite source effects (“shot noise”) and potentially large-scale structure. Current PTA GWB anisotropy detection methods often use the frequentist PTA optimal statistic for its fast estimation of pulsar pair correlations and relatively low computational overhead compared to spatially correlated Bayesian analyses. However, there are critical limitations with the status quo approach. In this paper, we improve this technique by incorporating three recent advancements: accounting for covariance between pulsar pairwise estimates of correlated GWB power, the per-frequency optimal statistic to dissect the GWB across the spectrum, and constructing null-hypothesis statistical distributions that include cosmic variance. By combining these methods, our new pipeline can localize GWB anisotropies to specific frequencies, through which anisotropy detection prospects—while impacted by cosmic variance—are shown to improve in our simulations from a $p$ value of $\sim 0.2$ in a broadband search to $\sim 0.01$ in the per-frequency search. Our methods are already incorporated in community-available code and ready to deploy on forthcoming PTA datasets.

Polarimetric interferometry is a powerful tool for probing both black hole accretion physics and the background spacetime. Current models aimed at explaining the observed multiwavelength flares in Sgr A* often assume hotspots moving on geodesic, Keplerian orbits. In many scenarios, though, a hotspot may instead follow an inspiraling trajectory, potentially transitioning into a plunge toward the black hole. In this work, we present a general framework to simulate the polarized emission from generic equatorial inspiraling hotspots in Kerr spacetime using a parametric four-velocity profile. This parametrization defines a continuous family of flows, ranging from Cunningham’s disk model (fixed radius orbits outside the innermost stable circular orbit and plunging motion within the innermost stable circular orbit) to purely radial motion, thereby extending the standard assumptions. Within this framework, we show that inspiral motion produces a distinctive observational signature: a precessing, unwinding evolution of the polarimetric Stokes $Q\text{−}U$ looping pattern, in sharp contrast with the closed $Q\text{−}U$ loops associated with stable orbits at a fixed radius. We then explore how the morphology of these signatures depends on black hole spin, observer inclination, and magnetic-field configuration. The presented model can be applied to current and near-future interferometric observations of linear polarization, offering a new avenue to probe the physics of matter spiraling inward and the relativistic velocities of plunging plasma.

We study a model in which a new interactions between the Standard Model (SM) photon and both the dark photon (${\gamma }_D$) and an axionlike particles (ALP or $a$) are described by the dark axion portal operator. The implications of this dark axion portal scenario for electron fixed-target experiments are presented. In particular, we investigate the missing energy signatures associated with production of dark photons and their subsequent invisible decays into stable dark sector fermions, ${\gamma }_D\to \chi \overline{\chi }$. We discuss the discovery potential for such a scenario and derive projected sensitivity curves for the $\mathrm{NA}64e$ and LDMX experiments. Furthermore, novel constraints of the $\mathrm{NA}64e$ for $9.37\times {10}^{11}$ electrons on target are derived by considering two production mechanisms for invisible states: (i) the bremsstrahlung-like emission of an $a{\gamma }_D$ pair, $eN\to eN{\gamma }^{*}(\to a{\gamma }_D)$, and (ii) the exclusive vector meson photoproduction, ${\gamma }^{*}N\to NV$, followed by the invisible decays of vector mesons, $V\to a{\gamma }_D$. Additionally, the constraints on the parameter space of $CP$-violating, fermion-specific ALP and dark photon couplings are established. These constraints are derived from current experimental bounds on the electric dipole moments (EDMs) of SM fermions, incorporating loop-induced contributions to the EDMs of the electron, muon, and neutron.

Recent measurements by the Belle II Collaboration report a branching ratio for the decay $B^{+}\to K^{+}\nu \overline{\nu }$ with a $3.5\sigma$ significance and deviating by $2.7\sigma$ from Standard Model expectation. In this article, we interpret this experimental result through the lens of a nonminimal universal extra dimensional model, where the mass profiles and interactions among various Kaluza-Klein states differ remarkably from those in the minimal scenario. Our analysis indicates that, according to the model’s parameters, the lower limit on the inverse of the compactification radius has been elevated to approximately 900 GeV. In contrast, conducting the same analysis within the model variant in which all boundary terms are nullified does not permit the determination of a lower bound on the inverse compactification radius.

We present a lattice QCD study of the chiral properties of ($2+1$)-flavor QCD in background magnetic fields at zero temperature with physical pion masses. Simulations are performed using the highly improved staggered quark action across four different lattice spacings to enable a controlled continuum extrapolation. We compute the renormalized chiral condensates together with pseudoscalar meson masses and decay constants for pions, kaons, and the fictitious ${\eta }_{s\overline{s}}^0$ pseudoscalar as functions of the magnetic-field strength $eB$ up to $eB\simeq 1.2{\mathrm{GeV}}^2$. The chiral condensates exhibit clear magnetic catalysis, increasing monotonically with the field strength. In the meson sector, neutral pseudoscalar masses decrease steadily with $eB$, whereas charged pseudoscalar masses display a nonmonotonic response: They rise at small fields, consistent with the lowest-Landau-level expectation, but then saturate and slightly decrease at larger fields, signaling sizable internal-structure effects. At the same time, neutral pseudoscalar decay constants are strongly enhanced by the magnetic field. To quantify deviations from chiral symmetry relations, we isolate the magnetic-field-induced shift in the Gell-Mann–Oakes–Renner corrections and find it to remain small for the neutral pion but to become sizable for the neutral kaon. To elucidate the origin of the magnetic response, we separately analyze the sea- and valence-quark contributions to both neutral and charged meson masses, finding that valence effects dominate at zero temperature. These results provide new insights into the interplay between QCD chiral symmetry breaking and strong magnetic fields.

The thermodynamic geometry of the hadron resonance gas model with (without) excluded volume effects (EVE) of baryons is investigated. The case with imaginary $\mu$, where $\mu$ is the baryon chemical potential, is investigated as well as the one with real $\mu$. We calculate the scalar curvature $R$ and use the $R=0$ criterion to investigate the phase structure in the ${\mu }^2-T$ plane where $T$ is the temperature. The curve on which $R=0$ continues analytically from the imaginary $\mu$ region, where the lattice QCD is feasible, to the real $\mu$ one. In the presence of EVE, there are rich phase structures in the large real $\mu$ region as well as the Roberge-Weiss-like region where $\mu$ is imaginary and a singularity appears, while there is no phase structure in the large real $\mu$ region in the absence of EVE. The limiting temperature of the baryon gas is also obtained by using the baryon number fluctuation. The LQCD predicted critical point locates almost on the curve of the limiting temperature we determined. A simple empiric sufficient condition, $n_{\mathrm{B}}>1/(2v_{\mathrm{B}})$, is obtained for the quark deconfinement in the large real $\mu$ region, where $n_{\mathrm{B}}$ and $v_{\mathrm{B}}$ are the net baryon number density and the volume of a baryon, respectively.

Vector boson scattering (VBS) serves as a powerful channel for probing the Standard Model (SM), particularly the electroweak symmetry breaking mechanism. Currently, studies of VBS mainly focus on $2\to 2$ scattering. In this study, we investigate the $2\to 3$ VBS process of $\mathrm{pp}\to Z\gamma \gamma +2\mathrm{jets}$ through Monte Carlo simulations, including signal generation and background analysis. The signal significance is evaluated across different phase-space regions. With an integrated luminosity of $500{\mathrm{fb}}^{-1}$, the signal significance can reach about $4.5\sigma$. Furthermore, the analysis is extended to a beyond the SM scenario involving Higgs boson decays into a $Z$ boson and an axionlike particle, providing projected exclusion limits on the relevant coupling parameters. These results suggest that, given the ongoing release of the LHC Run 3 dataset, there will be promising opportunities to explore and potentially discover a series of $2\to 3$ VBS processes, starting with the $Z\gamma \gamma$ channel.

We present a systematic exploration of conformal field theories (CFTs) constrained by duality-inspired fusion rules using the conformal bootstrap. We classify the operator spectrum into three sectors: [$\sigma$], [$\epsilon$], and $[1]$. The [$\sigma$] sector consists of all ${\mathbb{Z}}_2$-odd operators. The ${\mathbb{Z}}_2$-even operators are further divided into the [$\epsilon$] sector, which contains only the operators that change sign under duality, and the $[1]$ sector, which encompasses all remaining operators. We impose a selection rule motivated by Kramers-Wannier duality, specifically forbidding the appearance of the [$\epsilon$] sector in the $[\epsilon ]\times [\epsilon ]$ operator product expansion. By applying this constraint to the lowest-lying relevant scalars, we derive bounds on their conformal dimensions $({\mathrm{\Delta }}_{\sigma },{\mathrm{\Delta }}_{\epsilon })$ in dimensions $d=2$ through $d=7$. Our bounds correctly allow the $d=2$ Ising model while excluding the $d=3$ Ising model, demonstrating the effectiveness of the imposed condition. Furthermore, we observe a distinct feature in $d=2$ corresponding to the $\mathcal{M}(8,7)$ minimal model and find nontrivial constraints in $d=3$ (${\mathrm{\Delta }}_{\sigma }\gtrsim 0.85$), relevant for theories like ${\mathrm{QED}}_3$. This work opens a new avenue for nonperturbatively probing the landscape of CFTs constrained by fusion rules.

We study the gravitational form factors of the proton and some of its mechanical properties. We use a holographic model based on the AdS/CFT correspondence, in which a deformation in the anti–de Sitter background geometry is considered. By describing the proton as a Dirac field in this background, we numerically evaluate the gluon contribution of its gravitational form factors $A$ and $C$ from its energy-momentum tensor. A comparison of our numerical results with respect to some lattice QCD results and previous results in holography is made. In general, a good agreement is found. We also evaluate the term $D$ and make use of it to compute the pressure and shear distributions in the system, which result in a stable composed particle interpretation consistent with the von Laue stability condition. The energy distribution in the system is also obtained. Internal forces are investigated to support this picture. We are also able to compute the radii associated with these distributions in the proton.

We study the quantum dynamics of a probe scalar field in the background of a black hole in asymptotically AdS spacetime in the Hamiltonian formulation of general relativity in the maximal slicing gauge. The black hole solution in this gauge is expressed in terms of “wormhole coordinates,” a smooth coordinate system with constant time slices that cut across the horizon and asymptote to the Killing time slices at the boundaries. The quantum scalar field is expanded in terms of normalized solutions of the Klein-Gordon equation that are valid at all points in spacetime. The operators that appear in the expansion are in the product space of the CFTs on the two spacetime boundaries, which are by definition gauge invariant under small bulk diffeomorphisms. The entangled Hartle-Hawking (HH) state arises naturally from this construction. One of our main results is a well-defined formula, within effective field theory, for the time-dependent Hermitian Hamiltonian of the probe scalar in the product space of the two CFTs, which describes the time development of operators and states along the maximal slices. This Hamiltonian acting on the HH state creates a state of finite norm. Consequently, there is a unitary description of horizon crossing scalar field excitations on top of the HH state. We also present a bulk reconstruction formula that evaluates an order parameter that signals horizon crossing in the boundary theory. We calculate various bulk Wightman two-point functions on the two-sided Bañados-Teitelboim-Zanelli black hole. We recover Hawking’s thermodynamic results in the exterior region when expressed in terms of Bañados-Teitelboim-Zanelli coordinates that are related to the wormhole coordinates by a transformation which is singular at the horizon. We compute the two-point function with one insertion in the future or past interior and the other in the exterior. Both are related by a time reflection symmetry and asymptote to a nonzero constant as the coordinate time between the two points becomes large.

We solve Einstein’s equations with negative cosmological constant in $2+1$ dimensions in the Hamiltonian formulation. The spacetime has the topology of $\mathrm{\Sigma }\times \mathbf{R}$, where $\mathbf{R}$ corresponds to the time direction and $\mathrm{\Sigma }$ is a cylinder $\mathbf{R}\times {\mathbf{S}}^1$, and the spacetime metric satisfies asymptotically AdS boundary conditions. We address the question of gauge invariance by fixing the maximal slicing and spatial harmonic gauge conditions and demonstrate that there are no residual small diffeomorphisms in this gauge. We explicitly solve the Hamiltonian and momentum constraints and the gauge conditions to obtain a two-dimensional reduced phase space. We also solve for the lapse and shift functions in the above choice of gauge. For simplicity, and with the Bañados-Teitelboim-Zanelli (BTZ) black hole in mind, we restrict the solution of the momentum constraints and the lapse and shift functions to be independent of ${\mathbf{S}}^1$. More generally, one can consider an infinite set of solutions labeled by the angular momentum around the ${\mathbf{S}}^1$ which are related to the Virasoro algebra of the boundary CFT and boundary gravitons, but we do not consider this generalization here. In asymptotically AdS spacetimes besides the standard Wheeler-DeWitt equations there is a Schrödinger equation corresponding to the boundary Arnowitt-Deser-Misner Hamiltonian. We express this Hamiltonian in terms of the reduced phase space variables and discuss its classical solutions and quantization. We exhibit the wave functions and a continuous positive energy spectrum. Each energy eigenvalue $E$ corresponds to a BTZ black hole of mass $M=E/2$. This identification is based on the fact that the classical solution of the reduced phase space dynamics gives rise to a spacetime that is related to the two-sided BTZ black hole by a diffeomorphism.

We revisit the question of conformal boundary conditions in the compact free boson CFT in two dimensions. Besides the well-known Neumann and Dirichlet cases, there is an additional proposed one-parameter family of boundary states when the radius is an irrational multiple of the self-dual radius. These additional states have a continuous open string spectrum, and we give an explicit formula for the density of states. We also discuss several pathologies of these states, including the possible violation of the cluster condition, and that they have a divergent $g$ function.

Models of effective stellar collapse inspired by loop quantum gravity predict a bounce when the stellar energy density reaches the Planck scale, typically followed by the formation of shell-crossing singularities. This work aims to extend the spacetime beyond these singularities by employing a Hamiltonian formulation of the Darmois-Israel junction conditions, treating the singularity as a nonisolated thin dust shell. By construction, the shell’s motion remains timelike throughout the entire evolution, regardless of the amount of initial stellar mass, and the induced metric on the shell remains continuous. The resulting stellar evolution produces an inter-universal wormhole, analogous to the simpler Oppenheimer-Snyder scenario. The proposed approach provides a general framework for any effective (or classical) theory of stellar collapse characterized by shell-crossing singularities.

Effective field theories arising from string compactifications are subject to constraints originating from the duality transformations of string theory. Interpreting these so-called selection rules in terms of conventional symmetries has remained challenging. We show that particular selection rules in heterotic orbifolds can be explained from a subtle interplay between modular and traditional flavor symmetries within the eclectic flavor framework.