We establish a precise formula relating the world sheet integral of the anti–de Sitter (AdS) Virasoro-Shapiro amplitude to the energy-energy correlator (EEC) in $\mathcal{N}=4$ super Yang-Mills theory at strong coupling. This mapping allows us to evaluate the coefficients of the AdS curvature expansion of the EEC in terms of the world sheet integral over a unit disk. To illustrate this idea, we explicitly compute the flat-space contribution and the first curvature correction to the EEC. Our results provide a rigorous description of the stringy energy flow, demonstrating how world sheet correlators imprint themselves on collider observables and offering a potential template for effective string descriptions of energy correlators in general gauge theories.

We obtain a nonrelativistic chiral massive higher-spin gravity in a deformed ${\mathrm{AdS}}_3$ spacetime by applying a Lifshitz deformation and subsequent null reduction to chiral massless higher-spin gravity in ${\mathrm{AdS}}_4$. Intriguingly, the vertices of this nonrelativistic theory are less constrained than the ones in the original $4d$ chiral massless theory since we do not have enough dynamical generators to fix the couplings uniquely. Anticipating higher-spin interactions should be suppressed, we propose a simple approximate mass-spin relation that interpolates between the relativistic and nonrelativistic regimes. With the proposed mass-spin relation, we observe that higher-spin interactions indeed become suppressed at large spins, consistent with low-energy physics. We conjecture that the holographic dual of the nonrelativistic chiral massive higher-spin gravity proposed in this work is a $2d$ nonrelativistic Landau-Ginzburg theory in the light-cone gauge. This nonrelativistic theory is expected to describe a two-fluid system with a $\lambda$-point constrained in one spatial dimension.

We construct a large number of exact solutions of three-dimensional gravity with heavy matter particles that generalize the construction of Antonini, Sasieta, and Swingle, argued to define CFT states dual to a spacetime with a closed baby-universe cosmology. Our construction starts with an arbitrary heavy-particle closed universe cosmology of the type constructed in Maloney, Meruliya, and Van Raamsdonk [arXiv:2503.12227] and via a gluing procedure adds an arbitrary number of AdS tubes connecting the past and future conformal boundaries of the associated Euclidean wormhole solution. With our construction, it is straightforward to produce examples where the cosmology is approximately homogeneous and isotropic. We describe a necessary condition for the cosmological wormhole saddle to dominate the Euclidean path integral with the specified boundary conditions. We argue that the original Antonini-Sasieta-Swingle construction usually does not meet this condition and describe alternative saddles that are likely to dominate. We discuss various possibilities for how the cosmological saddle might be made to dominate in our generalized construction.

We recently introduced a recursive bootstrap method for constructing $n$-point gluon and graviton Mellin-momentum amplitudes in (A)dS spacetime. The power of this approach was illustrated by our successful computation of the first five-point graviton amplitude in (A)dS. In this work, we provide further details of these calculations and start with a more in-depth review of the formalism by offering detailed insights into the motivation for defining on-shell amplitudes in AdS, along with various explicit examples. Furthermore, we demonstrate how cosmological correlators can be effortlessly obtained once the amplitude is determined.

We present an approach to deriving positivity bounds on effective field theories by analyzing the thermodynamic behavior of thermal quantum field systems. Focusing on scalar theories with higher-dimensional operators, we compute the finite-temperature entropy using thermal field theory techniques. We argue that consistency with fundamental thermodynamic principles—specifically, the expectation that entropy increases with the introduction of new degrees of freedom—imposes nontrivial constraints on Wilson coefficients. In particular, we show that the coefficient of the leading dimension-eight operator must be strictly positive. This thermodynamic perspective offers an alternative to traditional $S$-matrix-based derivations of positivity bounds and provides a complementary perspective on the interplay between entropy, unitarity, and causality in quantum field theory.

In the Cachazo-He-Yuan (CHY) representation, many tree-level scattering amplitudes are written as integrals localized by the scattering equations, where the CHY integrand encodes the theory and must reproduce the physical factorization pattern of Mandelstam singularities. The inverse CHY problem therefore asks for a rational integrand whose physical poles match a prescribed set of factorization channels, a task that becomes rapidly combinatorial at higher multiplicity. We present an algorithmic approach that makes the subset structure of pole data explicit by assigning each particle subset $A$ a generalized pole degree $K(A)$, realized as a signed internal-edge count in a colored integrand graph. Additivity under integrand multiplication and an elementary face recursion on the subset lattice imply that all higher-channel $K(A)$ are linear functions of the two-particle integers $\{K(s_{ij})\}$, so the inverse step becomes a mixed-integer linear feasibility problem. The same subset lattice provides a fixed computation graph for exact constraint satisfaction: pole requirements and recursion identities are treated as hard constraints, updates are restricted to those that preserve feasibility, and whenever a proposed change would enter a fixed node its constraint residual is rerouted and redistributed through unfixed degrees of freedom so that all constraints remain satisfied throughout. After a factorial rescaling, every local propagation update is purely integral, keeping the entire procedure exact in integer arithmetic and avoiding a posteriori reconstruction from numerical evaluations. Since physical tree-level amplitudes must contain only simple factorization poles as dictated by unitarity and locality, we further organize generalized integrands by an $n$-regular grading under multiplication, where degree-zero factors act as Möbius-invariant insertions admitting a decomposition into products of four-point cross ratios, which guides efficient higher-order pole reduction. We illustrate the construction at six and eight points, including pole selection and higher-order pole reduction.

We uncover a new class of phenomena in gravitational physics, whereby resonances in the complex plane can be excited via tailored time-dependent scattering. We show that specific forms of temporal modulation of an incoming signal can lead to complete absorption for the entire duration of the scattering process. This, then, makes stars and black holes truly black. Such “virtual absorption” stores energy with high efficiency, releasing it once the process finishes via relaxation into the characteristic virtual absorption modes—also known as total transmission modes—of the object. While such modes are challenging to obtain and four-dimensional black holes have a restricted set of solutions, we also show that higher dimensional black holes have a complex and interesting structure of virtual absorption modes.

Using state-of-the-art scattering results in post-Minkowskian (PM) gravity, we improve the tidal sector of four different flavors of the effective-one-body (EOB) formalism. We notably explore both adiabatic and postadiabatic gravitoelectric and gravitomagnetic quadrupolar tidal effects at the next-to-next-to-leading PM order. When comparing the predictions of the so-constructed Lagrange-PM-tidal version of EOB to recent numerical-relativity data on the scattering of neutron stars, we find improved agreement with respect to existing EOB models and PM expansions. Our work lays the foundation for the development of an accurate tidal sector of the PM EOB models, and points out the need to explore improved resummation schemes in PN EOB for bound and circularized orbits.

We investigate metric perturbations of a spherically symmetric black hole in higher curvature gravity. We show that higher curvature corrections deform the near-horizon region of the effective potential, and that the deviations of the quasinormal mode (QNM) frequencies from their general relativity (GR) values become more pronounced for overtone modes. We find that, as the order of the higher curvature term increases, the deformations approach the horizon and the deviations of the overtone QNM frequencies grow progressively larger. We also analyze the ringdown waveforms in the higher curvature gravity model. We consider setups in which the deviations from the vacuum-GR QNMs remain mild for the fundamental mode and the first few overtones, and show that these shifted QNMs can be identified in the ringdown signal through waveform fitting.

We carry out the first computation of gravitational quasinormal modes of black holes with arbitrary rotation in a theory with higher-derivative corrections. Our analysis focuses on a recently identified quartic curvature theory that preserves the isospectrality of quasinormal modes in the eikonal limit and that is connected to string theory. We find a master equation that governs large-momentum gravitational perturbations in this theory. By solving this equation with Wentzel-Kramers-Brillouin methods, we provide complete results for the corrections to the Kerr quasinormal mode frequencies for arbitrary spin and arbitrary $\mu =m/(\ell +1/2)$, where $\ell$ and $m$ are the harmonic numbers. Our results show that the corrections become orders of magnitude larger when the spin is close to extremality, with the modes close to the critical value of $\mu$ that separates damped and zero-damped modes being particularly sensitive. We also perform a geometric optics analysis of gravitational wave propagation around black holes and relate the equatorial “graviton sphere” orbits to quasinormal mode frequencies with $\ell =m$. We find that the usual correspondence between the Lyapunov exponent of those orbits and the imaginary part of the frequency is modified.

We present a strong-deflection expansion for the deflection angle of light rays scattered near a degenerate photon sphere in asymptotically flat, static, and spherically symmetric spacetimes. Our prescription isolates the divergent contribution to the deflection-angle integral arising from the ray’s passage near the marginal orbit in a way that remains nonsingular at marginality, thereby yielding a unique leading power-law term. When expressed in terms of the radius of closest approach, the leading coefficient in the strong deflection limit factorizes into a universal branch constant and a local factor determined by the third derivative of the effective potential at the degenerate photon sphere. When the expansion is rewritten in terms of the impact parameter, the coefficient is simply multiplied by an additional local conversion factor. We show that the local factor in the closest-approach expansion admits an invariant representation through the areal-radius derivative of a dimensionless tidal measure constructed from the electric part of the Weyl tensor. In general relativity, we further relate this quantity to the areal-radius derivative of a weighted null-energy density profile. Analytic examples validate this factorization and yield closed-form expressions for the leading divergent coefficients in representative marginal configurations.

General relativity can be reconciled with quantum field theory without quantizing the geometry only if the metric evolves stochastically. In this article, we explore the consequences of such a proposal at early cosmological times. We find the stochastic evolution results in the spatial metric diffusing away from its deterministic value, generating phantom cold dark matter (CDM). It is produced primarily at the end of the inflationary phase of the Universe’s evolution, with a statistical distribution that depends on the specifics of the early times cosmological model. We find the energy density of this phantom cold dark matter is positive on average, a necessary condition to reproduce the cosmological phenomenology of CDM, although further work is required to calculate its mean density and spatial distribution. If the density is cosmologically significant, phantom dark matter acts on the geometry in a way that is indistinguishable from conventional CDM. As such, it has the potential to reproduce phenomenology such as structure formation, lensing, and galactic rotation curves. We conclude by discussing the possibility of testing hybrid theories of gravity by combining measurements of the cosmic microwave background with tabletop experiments.

We investigate the effective quantum evolution of the Bianchi type I cosmological model within the Brans-Dicke framework, using an effective Hamiltonian approach including expectation values, quantum dispersions, and cross-correlation terms between different degrees of freedom. We show that cross-correlation terms are essential for a physically consistent effective dynamics: neglecting them leads to spurious divergences, violation of the Heisenberg uncertainty relations, and unphysical behavior. For $\omega <-3/2$, where bouncing solutions exist already classically, quantum backreaction smooths the bounce and suppresses shear anisotropy, and the energy density peak is slightly enhanced and remains well behaved, in contrast to the unphysical divergences that arise when cross-correlations are neglected. For the conformally invariant case $\omega =-3/2$, quantum corrections accelerate the approach to de Sitter expansion while enhancing shear anisotropy. When correlations are included, small-amplitude damped oscillations appear shortly after the bounce, which we interpret as quantum remnant effects encoding Planck-scale correlation information between gravitational and scalar field degrees of freedom. The effective energy density remains finite for both regimes. Our results demonstrate that cross-correlations carry crucial quantum information influencing cosmological dynamics, with implications for quantum gravity phenomenology, inflationary model building, and primordial observational signatures.

The peculiar velocities of dark matter tracers drive the growth of cosmic structures, providing a sensitive test of cosmological models and strengthening constraints on the nature of dark energy. In this work, we investigate the mean pairwise velocities, $v_{12}$, of dark matter tracers as a cosmological probe in the nonlinear regime of cosmic structure formation. Using $N$-body dark matter-only simulations, we measure $v_{12}$ for pair separations up to $50h^{-1}\mathrm{Mpc}$ and model it by solving the pair conservation equation for a self-gravitating particle system, along with various prescriptions of the nonlinear matter power spectrum. We quantified the sensitivity of $v_{12}$ to variations in key cosmological parameters such as ${\mathrm{\Omega }}_{\mathrm{m}}$, ${\sigma }_8$, $h$, $M_{\nu }$, and $w$. Our parameter inference analysis using Markov chain Monte Carlo (MCMC) shows sub-11% agreement with simulation data, with notable degeneracies, particularly between ${\mathrm{\Omega }}_m$ and ${\sigma }_8$. We further compute the stable clustering crossing scale across redshifts $z=0$, 0.5, and 1, assessing its dependence on cosmology. Among the tested power spectrum modeling approaches, we find that the csstemu emulator provides the most accurate predictions, with deviations below 5% for $r>10h^{-1}\mathrm{Mpc}$ at $z=0.5$. Our results are validated using independent simulation suites, demonstrating that our framework offers a robust method for extracting cosmological constraints from upcoming peculiar velocity data.

The neutron star–black hole (NSBH) binary GW200105 was recently found to have significant residual orbital eccentricity at a gravitational-wave frequency of 20 Hz [G. Morras et al., Orbital eccentricity in a neutron star—black hole binary, Astrophys. J. Lett. 1000, L2 (2026)]. The event was originally identified with moderate significance by matched-filter searches that employ noneccentric templates. The neglect of relevant physical effects, such as orbital eccentricity, can severely reduce the sensitivity of the search and, consequently, also the significance of an event candidate. Here, we present a targeted eccentric search for GW200105. The eccentric search identifies GW200105 as the most significant event with a signal-to-noise ratio of 13.4 and a false alarm rate of less than 1 in 1000 years. The best-matching template parameters are consistent with the Bayesian inference result, supporting the interpretation of GW200105 as an NSBH that formed through dynamical mechanisms including hierarchical triples and not via isolated binary evolution.

While the majority of gravitational wave (GW) events observed by the LIGO and Virgo detectors are consistent with mergers of binary black holes (BBHs) on quasicircular orbits, some events are also consistent with nonzero orbital eccentricity, indicating that the binaries could have formed via dynamical interactions. Moreover, there may be GW events which show support for spin precession, eccentricity, or both. In this work, we study the interplay of spins and eccentricity on the parameter estimation of GW signals from BBH mergers. We inject eccentric signals with no spins, aligned spins, and precessing spins using hybrids, teobresums-dali, and new numerical relativity simulations, respectively, and study the biases in the posteriors of source parameters when these signals are recovered with a quasicircular precessing-spin waveform model, as opposed to an aligned-spin eccentric waveform model. We find significant biases in the source parameters, such as chirp mass and spin precession (${\chi }_p$), when signals from highly eccentric BBHs are recovered with a quasicircular waveform model. Moreover, we find that for signals with both eccentricity and spin-precession effects, Bayes factor calculations confirm that an eccentric, aligned-spin model is preferred over a quasicircular precessing-spin model. Our study highlights the complex nature of GW signals from eccentric, precessing-spin binaries and the need for readily usable inspiral-merger-ringdown eccentric, spin-precessing waveform models for unbiased parameter estimation.

We predict the gamma-ray line emission from $r$-process nuclei synthesized in the ejecta of the accretion-induced collapse (AIC) of a magnetized, rapidly rotating white dwarf. Using ejecta from a two-dimensional general-relativistic neutrino-magnetohydrodynamic simulation, further evolved with a radiation-hydrodynamics code coupled to an in situ nuclear reaction network, we construct angle-dependent gamma-ray spectra in the 0.01–10 MeV band via composition-dependent ray tracing through the ejecta. The emission between $\sim 1$ and 10 d is dominated by ${}^{132}\mathrm{I}$ ($t_{1/2}=2.3\mathrm{h}$), continuously replenished by the decay of its parent ${}^{132}\mathrm{Te}$ ($t_{1/2}=3.2\mathrm{d}$), with additional contributions from ${}^{131}\mathrm{I}$, ${}^{133}\mathrm{Xe}$, and ${}^{132}\mathrm{Te}$. At $t\gtrsim 20\mathrm{d}$, ${}^{56}\mathrm{Co}$ (from ${}^{56}\mathrm{Ni}$ decay) becomes the primary emitter. The simultaneous presence of $r$ process and iron-peak gamma-ray lines is distinctive of AIC ejecta and absent in binary neutron star mergers, where iron-peak nuclei are generally not synthesized. Comparing with the $3\sigma$ continuum sensitivities of planned MeV gamma-ray telescopes (COSI, AMEGO-X, e-ASTROGAM, GRAMS, GammaTPC), we find the brightest $r$-process lines detectable to $\sim 10\mathrm{Mpc}$ by GammaTPC and GRAMS, with the signal approaching their sensitivity threshold at 30 Mpc. The $r$-process spectral features survive time integration over $\sim 30$ d exposures, demonstrating robustness against the long observation times required by gamma-ray detectors.

Binary black holes (BBHs) exhibiting spin-induced orbital precession offer unique insight into compact-binary formation channels, cosmology, and tests of general relativity. We conduct a dedicated search for precessing BBHs with unequal masses in Advanced LIGO’s third observing run (O3) using the harmonic decomposition method of precessing waveforms. We introduce a novel scheme to reduce the number of filters in a harmonic search. With our new approach, our template bank requires $5\times$ fewer filters compared to another proposed precessing search in the same region. We do not find any new significant events. Our new search method achieves up to $\sim 28\%$ improvement in sensitivity and up to $5\times$ lower computational costs compared to existing precessing search pipelines. Our method enables scalable, sensitive searches for precessing BBHs in future gravitational-wave observing runs.

Coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) has been experimentally confirmed using neutrinos from pion decay at rest, solar neutrinos, and reactor antineutrinos. Future $\mathrm{CE}\nu \mathrm{NS}$ experiments will lead to precision measurements, which will be a powerful tool to search for new physics beyond the standard model. In this work, we investigate possible deviations from unitarity in the $3\times 3$ leptonic mixing matrix that controls the propagation of active neutrinos. Such deviations may originate from the mixing with additional gauge singlet fermions, and depending on their mass scale and mixing, the resulting phenomenology can differ substantially. We explore two well-motivated regimes: the seesaw limit, where the new fermions are heavy and kinematically inaccessible, leading to effective deviations from unitarity in the active sector, and the light sterile limit, where they are light enough to be produced and participate in neutrino propagation and scattering processes. We show how these scenarios modify both $\mathrm{CE}\nu \mathrm{NS}$ and elastic neutrino-electron scattering, and we present the corresponding sensitivity projections for a future $\mathrm{CE}\nu \mathrm{NS}$ reactor experiment obtained by upscaling the CONUS+ experiment, which reported the first observation of reactor $\mathrm{CE}\nu \mathrm{NS}$. We identify the leading experimental systematics relevant for such an upscaling and demonstrate the resulting capability to probe TeV-scale new physics. Our results highlight the strong potential of $\mathrm{CE}\nu \mathrm{NS}$ to test the structure of the lepton sector and to search for physics beyond the standard model.

Generalized neutrino interactions (GNI) are emerging as a convenient framework for describing effective scalar, vector, and tensor interactions. Such interactions arise naturally from extensions of the Standard Model that aim to explain neutrino properties and their mass origin. In this paper, we carefully study the two more common parametrizations for GNI and how to relate them. This allows us to compare bounds obtained from coherent elastic neutrino-nucleus scattering (CEvNS) and deep-inelastic scattering under the same footing. In addition, we present the current bounds from CEvNS measurements by COHERENT and compare them to those obtained from deep inelastic scattering on the same level. Our results focus on neutrino-quark interactions, and illustrate the complementarity between experiments working at different scales for GNI, showing that scalar interactions are better constrained by low-energy experiments like COHERENT, while tensor interactions are robustly constrained from deep inelastic scattering.