Recent lattice QCD simulations and phenomenological models indicate that the nucleon’s gravitational form factor $B_N(t)$ remains remarkably small at finite momentum transfer $t$. While $B_N(0)=0$ is a known consequence of the equivalence principle, the physical origin of its suppression at finite $t$ has not been fully elucidated. In this work, we demonstrate that the smallness of $B_N(t)$ arises from a fundamental cancellation within the nucleon’s wave functions. Using light-front holographic QCD, we show that $B_N(t)$ is governed by an antisymmetric factor in the longitudinal dynamics that leads to an exact vanishing in the symmetric limit and significant suppression for realistic nucleon structures. Our results suggest that the smallness of $B_N(t)$ is a signature of the nucleon’s dominant S-wave character, providing a formal justification for its frequent omission in practical applications like near-threshold $J/\psi$ production.

A dispersion integral representation of the Heisenberg-Euler QED effective Lagrangian is derived, with Faddeev’s quantum dilogarithm as a generalized Borel kernel. The nonperturbative imaginary part of the effective Lagrangian is expressed as the quantum dilogarithm, while the real part has the form of a dispersion integral involving both the quantum dilogarithm and its modular dual, a manifestation of electromagnetic duality. The Heisenberg-Euler effective Lagrangian generates all one-loop QED scattering amplitudes in a constant external field, with the Lorentz invariants of the constant background electromagnetic field playing the role of the Mandelstam variables in conventional QED dispersion theory.

We quantify the transition between weak and strong coupling in thermal $\mathcal{N}=4$ supersymmetric Yang-Mills theory in four space-time dimensions by constructing an admissible ensemble of log-aware Padé approximants that incorporate the weak- and strong-coupling expansions through $\mathcal{O}({\lambda }^2)$ and $\mathcal{O}({\lambda }^{-3/2})$ ($\lambda$ is the ’t Hooft coupling), including the nonanalytic ${\lambda }^{3/2}$ and ${\lambda }^2\log \lambda$ terms. This replaces single-curve estimates with a reproducible uncertainty band and a well-defined central curve across the intermediate regime. The framework is predictive, setting testable benchmarks for forthcoming perturbative and holographic calculations.

We re-examine the Klein paradox from a many-particle perspective in quantum field theory. Specifically, we compute the expectation value of the particle current induced by a sufficiently strong steplike electric potential in $1+1$ dimensions. First, for a constant (eternal) potential, we calculate the current for different Fock space ground states corresponding to distinct mode bases. While one basis yields a zero current, another produces the standard nonzero value. We then consider a potential that is rapidly switched on, recovering the standard current in the asymptotic future. This result is generalized to potentials that interpolate between different constant values at spatial infinity. Finally, we analyze a potential acting for a finite duration and again reproduce the standard current. A physical interpretation of these results is provided.

We present the most general and exact solution of Einstein’s gravity sourced by an anisotropic fluid describing the cosmological embedding (CE) of a static and spherically symmetric object, including black holes (BHs) or exotic compact objects, without radial energy influx and in an arbitrary Friedmann-Lemaître-Robertson-Walker cosmology. This is done fully considering backreaction of the local geometry on the cosmological dynamics. Our solution is free of curvature singularities at the would-be BH event horizon, thus solving a main issue of the CE of BH solutions proposed so far. As a by-product, we derive a new CE of the Schwarzschild BH—distinct from McVittie’s original proposal—that is regular everywhere except at the central singularity.

The Laser Interferometer Space Antenna (LISA) is a planned space-based observatory designed to detect gravitational waves within the millihertz frequency range. LISA is anticipated to observe the inspiral of compact objects into black holes at the centers of galaxies, so-called extreme-mass-ratio inspirals (EMRIs). However, the extraction of these long-lived complex signals is challenging due to the large size and multimodality of the search space. In this study, we introduce a new search strategy that allows us to find EMRI signals in noisy data from wide priors all the way to performing parameter estimation. This work is an important step in understanding how to extract EMRIs from future LISA data.

Screened scalars are ubiquitous in many dark-sector models. They give rise to nontrivial fifth forces while evading experimental constraints through density-dependent screening mechanisms. We propose equipping a 10 m-scale long-baseline atom interferometer with an annular planar source mass inside the vacuum chamber to search for such screened fifth forces. Two key challenges arise: distinguishing the static fifth force from backgrounds, and isolating it from the plate’s Newtonian gravity. We introduce the $Q$-flip protocol, which alternates between interferometry sequences to induce controllable time-dependence, aiding signal extraction and detrending of transient noise. We further develop an in situ calibration procedure to characterize the plate’s Newtonian gravity and reach shot-noise-limited sensitivity. We show that our proposal could test theoretically motivated parameter space, advancing existing bounds on chameleon and symmetron screened scalar models by 1 to 1.5 orders of magnitude. Our proposal is directly applicable to forthcoming experiments, such as AION-10 or VLBAI, and is readily extensible to broader theoretical models and longer baselines.

The IceCube Neutrino Observatory has detected a flux of $\sim 1–10\mathrm{TeV}$ neutrinos from the active galaxy, NGC 1068. The soft spectral index of these neutrinos has previously been interpreted as an indication that this source accelerates protons only up to energies of several hundred TeV. Here, we propose that this source might instead accelerate protons to significantly higher energies, but that the charged pions and muons produced in their interactions undergo significant synchrotron energy losses before they can decay, leading to a cutoff in the neutrino spectrum at TeV-scale energies. This scenario would require very strong magnetic fields to be present in the acceleration region of NGC 1068, on the order of $B\sim {10}^7\mathrm{G}$. We point out that this synchrotron cooling would impact the flavor ratios of the neutrinos from this source, providing a means to test this scenario with future very-large volume neutrino telescopes.

Gravitational wave observations have recently revealed with high significance, and high precision, the existence of $\mathcal{O}(100)M_{\odot }$ rapidly rotating black holes, allowing gravitational wave events to be used for the first time to probe unexplored axion parameter space using the phenomenon known as black hole superradiance. Here, we present new limits on axions using the binary black hole merger event GW231123, whose constituent black holes are among the fastest spinning observed with gravitational waves to date. We demonstrate that the most viable binary formation channels lead to conservative constraints on axion masses $\mu \sim [0.6-5]\times {10}^{-13}\mathrm{eV}$ and decay constants $f_{\mathrm{\Phi }}\gtrsim {10}^{14}\mathrm{GeV}$, extending existing superradiance constraints derived using x-ray observations to yet lower axion masses.

Prompt cusps (PCs) form from the direct collapse of overdensities in the early Universe, reside at the center of every dark matter halo, and have density profiles steeper than $r^{-1}$ Navarro–Frenk–White (NFW) cusps. Using a suite of high-resolution N-body simulations, we study the evolution of isolated halos in self-interacting dark matter (SIDM) with massive PCs embedded at their centers, a scenario that could be realized in certain SIDM models with light mediators that predict a small-scale suppression of the linear matter power spectrum. We track the evolution of three equally concentrated ${10}^7{M}_{\odot }$ halos, hosting PCs of various total masses, and quantify how the presence of a PC affects the processes of core formation and collapse. Early in the core-formation phase, halos with more prominent PCs exhibit a delayed evolution by a factor of $\sim 2$ due to smaller velocity dispersion gradients in the inner region. During most of the core-collapse phase, the halo evolution becomes closely aligned in physical time, with appropriate rescaling of densities, radii, and velocity dispersions. The scale densities and radii preserve the virial mass of the original halos, but with increased concentration. Deviations occur at the late phase of core collapse at the level of $\sim 5\%$ relative to the reference collapse track of an NFW halo. These deviations depend nontrivially on both the increased concentration incurred by the PCs, as well as the velocity dispersion (temperature) of the outer halo regions, which can inhibit or enhance the heat transfer process. Our simulations illustrate the complex interplay between the inner and outer halo profiles in determining the onset of core collapse and motivate future studies in the full cosmological context.

In this work, we explore a possible application of a machine learning classifier for candidate events in a template-based search for gravitational-wave signals from various compact system sources. We analyze data from the O3a and O3b data acquisition campaign, during which the sensitivity of ground-based detectors is limited by real non-Gaussian noise transient. The state-of-the-art searches for such signals typically rely on the signal-to-noise ratio (SNR) and a chi-square test to assess the consistency of the signal with an inspiral template. In addition, a combination of these and other statistical properties are used to build “reweighted SNR” statistics. We evaluate a Random Forest classifier on a set of double-coincidence events identified using the multiband template analysis pipeline. The new classifier achieves a modest but consistent increase in event detection at low false positive rates relative to the standard search. Using the output statistics from the Random Forest classifier, we compute the probability of astrophysical origin for each event, denoted as $p_{\text{astro}}$. This is then evaluated for the events listed in existing catalogs, with results consistent with those from the standard search. Finally, we search for new possible candidates using these new statistics, with $p_{\text{astro}}>0.5$, obtaining a new subthreshold candidate (inverse false alarm rate $=0.05$) event at $gps:1240423628$.

A primary bottleneck in modern fast Fourier transform (FFT)-based matched-filter searches for gravitational waves from compact binary coalescences is not raw processor throughput, but available memory bandwidth. Standard frequency-domain implementations, such as the FINDCHIRP algorithm, rely on streaming long template waveforms and data from main memory, which leads to significant processor stalling when template durations exceed cache capacities. In this work, we introduce ratio-filter dechirping as a solution, an algorithmic restructuring of the matched filter that transforms the operation from a memory-bound FFT into a cache-efficient, compute-bound finite impulse response (FIR) convolution. By utilizing a reference template to remove common orbital phase evolution, we produce slowly changing frequency-domain ratios that can be accurately implemented as short FIR filters. This method delivers a measured speedup of $8\times$ for the core filtering loop used in offline searches and should enable $>10\times$ for low-latency analysis. We find that this approach generalizes to a variety of searches that include physical features such as finite size effects, eccentricity, and precession. By dramatically reducing the computational cost of matched filtering, this approach enables the expansion of searches into dense or high-dimensional parameter spaces, such as those for eccentric or subsolar-mass signals, that are already limited by available computing budgets. Furthermore, this framework provides a natural path for hardware acceleration on graphics processing unit architectures.

We demonstrate that novel limits on prompt axionlike particles (ALPs) in the hard-to-probe mass range near the neutral pion—the so-called pion chimney—may be obtained from recasting $K_L\to 3{\pi }^0\to 6\gamma$ data taken by the J-PARC KOTO experiment, to search for $K_L\to 2{\pi }^{0}a\to 6\gamma$. We also explore the power of KOTO $6\gamma$ data to probe $K_L\to 2{\pi }^{0}a$ for a broader range of ALP masses, incorporating displaced decays.

We present a calculable toy model of an axion coupled to magnetic monopoles and electric charges, with manifest electric-magnetic duality. Our axion-photon coupling incurs periodic corrections due to monopoles (equivalently UV instantons), which are large for light monopoles. Axion periodicity is manifestly duality invariant since the axion itself transforms under duality. Our model is the original Seiberg-Witten theory, which naturally hosts an $\mathcal{R}$-axion and light monopoles. We calculate the axion-photon amplitude in different duality frames and prove its duality invariance.

The classical and quantum simulation of lattice gauge theories (LGTs) with Lie groups is hindered by the infinite-dimensional Hilbert space of gauge degrees of freedom. In a recent work [P. Fontana et al., Efficient finite-resource formulation of non-Abelian lattice gauge theories beyond one dimension, Phys. Rev. X 15, 031065 (2025)], we introduced a new truncation scheme—here renamed as the renormalized dual basis (RDB)—based on the resolution of the single-plaquette problem, and demonstrated its performance for SU(2) LGTs. In this paper, we apply the RDB to compact quantum electrodynamics (in three spacetime dimensions (2+1D). We variationally determine the ground state of the theory for small lattices with periodic (for pure gauge) and open (in presence of fermionic matter) boundary conditions, achieving improved precision for the plaquette operator compared to previous approaches. By leveraging tensor networks, we extend the study to larger lattices and demonstrate the scalability of the method. Overall, we show that the RDB provides an efficient description across all coupling regimes.

We investigate the ($2+1$)-dimensional $q$-deformed $\mathrm{SU}(N{)}_k$ Yang-Mills theory in the lattice Hamiltonian formalism, which is characterized by three parameters: the number of colors $N$, the coupling constant $g$, and the level $k$. By treating these as tunable parameters, we explore how key properties of the theory, such as confinement and topological order, emerge in different regimes. Employing a variational mean-field analysis that interpolates between the strong- and weak-coupling regimes, we determine the large-$N$ phase structure in terms of the ’t Hooft coupling ${\lambda }_{\mathrm{tH}}=g^{2}N$ and the ratio $k/N$. We find that the topologically ordered phase remains robust at large $N$ under appropriate scalings of these parameters. This result indicates that the continuum limit of large-$N$ gauge theory may be more intricate than naively expected, and it motivates studies beyond the mean-field theory, both to achieve a further understanding of confinement in gauge theories and to guide quantum simulations of large-$N$ gauge theories.

We study energy-energy correlators (EECs) in $e^{+}{e}^{-}$ annihilation and deep inelastic lepton-hadron scattering (DIS), focusing on aspects of nonperturbative physics in these observables. We introduce the EEC jet functions and investigate the infrared behavior of both small-angle EECs and angle-integrated EECs by performing explicit one-loop calculations. The factorization and universality of the EECs in these processes are demonstrated. A matching scheme is proposed to smoothly connect kinematic regions where different scaling behaviors with jet energy are observed. In combination with the next-to-leading order correction, this matching provides a good description of the EEC data and pythia simulations in high-energy $e^{+}{e}^{-}$ annihilation. Predictions for DIS processes for future electron-ion collider kinematics are also presented.

The unique off-shell fermionic gauge invariance of a vector-spinor field theory is found, and the invariant action is derived. The latter is Weyl invariant in any dimension in the massless limit, and it coincides with the singular point of the one-parameter family of Rarita-Schwinger Lagrangians, in agreement with previous findings in flat space. Pure gauge configurations are represented by gamma-trace vector-spinors, which can be gauged away in a global fashion. Previous claims that this theory is classically inconsistent are shown to be flawed, and the Velo-Zwanziger instability is proved to be absent. The theory propagates a massive spin-$\frac{3}{2}$ particle together with a spin-$\frac{1}{2}$ state whose mass is twice that of the $j=\frac{3}{2}$ mode. The causal construction of the quantum field is consistent with the field equations in that the ratio of the masses is the same, while it shows that the lower-spin component is a negative-norm state. The conformal anomaly is derived using known results for the heat kernel of nonminimal second-order operators, and the resulting $a$ charge is negative consistently with the Hofman-Maldacena bound, which applies only to unitary theories.

We investigate the local characteristics of the Fulling-Rindler vacuum for a massive Dirac field induced by a planar boundary moving with constant proper acceleration in ($D+1$)-dimensional flat spacetime. On the boundary, the field operator obeys the bag boundary condition. The boundary divides the right Rindler wedge into two separate regions, called right-left (RL) and right-right (RR) regions. In both these regions, the fermion condensate and the vacuum expectation value (VEV) of the energy-momentum tensor are decomposed into two contributions. The first one presents the VEVs in the Fulling-Rindler vacuum when the boundary is absent and the second one is the boundary-induced contribution. For points away from the boundary, the renormalization is reduced to the one for the boundary-free geometry. The total VEVs are dominated by the boundary-free parts near the Rindler horizon and by the boundary-induced parts in the region near the boundary. For a massive field the boundary-free contributions in the fermion condensate and the vacuum energy density and effective pressures are negative everywhere. The boundary-induced contributions in the fermion condensate and the energy density are positive in the RL region and negative in the RR region. For a massless field the fermion condensate vanishes in spatial dimensions $D\ge 2$, while the VEV of the energy-momentum tensor is different from zero. This behavior contrasts with that of the VEVs in the Minkowski vacuum for the geometry of a boundary at rest relative to an inertial observer. In the latter case, the fermion condensate for a massless field is nonzero, while the VEV of the energy-momentum tensor becomes zero. The obtained results are used to investigate the VEV of the fermionic energy-momentum tensor in weak gravitational fields and background geometries that are conformally related to Rindler spacetime.

Black hole binaries with small mass ratios will be important sources for the forthcoming Laser Interferometer Space Antenna mission. Models of such binaries also serve as useful tools for understanding the dynamics of compact binary systems and the gravitational waves they emit. Using an eccentric Ori-Thorne procedure developed in previous work, we build worldlines that describe the full inspiral and plunge of a small body on an initially eccentric orbit of a Kerr black hole. We now calculate the gravitational waves associated with these trajectories using a code that solves the Teukolsky equation in the time domain. The final cycles of these waveforms, the ringdown, contain a superposition of Kerr quasinormal modes followed by a power-law tail. In this paper, we study how a binary’s eccentricity and orbital anomaly angle affect the excitation of both quasinormal modes and late-time tails. We find that the relative excitation of quasinormal modes varies in an important and interesting way with these parameters. For some anomaly angles, the relative excitations of quasinormal modes are essentially indistinguishable from those excited in quasicircular coalescences. Consistent with other recent studies, we find that eccentricity tends to amplify the late-time power-law tail, though the amount of this amplification varies significantly with orbital anomaly. We thus find that eccentricity has an important impact on the late-time coalescence waveform, but the interplay of eccentricity and orbit anomaly complicates this impact.