In this work we investigate curvature perturbations and non-Gaussianity arising from Higgs modulated reheating in the early Universe. We employ three different methods—the period-averaging (PA) method, the exact method, and the nonperturbative $\delta N$ formalism—to compute the power spectrum and bispectrum of curvature perturbations. Our results show that the nonperturbative $\delta N$ method provides a reliable estimate across a wide range of reheating time and Higgs field values, including regimes where the Higgs field oscillates significantly after inflation. We find that a smaller Higgs self-coupling ($\lambda$) leads to a larger curvature perturbation, with the non-Gaussianity predominantly taking a local shape. This highlights the importance of considering nonperturbative effects in calculating the curvature perturbation during Higgs modulated reheating, especially for smaller values of $\lambda$. Our findings offer valuable insights into the dynamics of reheating and the generation of primordial perturbations in the early Universe.

Quantum simulators offer great potential for investigating dynamical properties of quantum field theories. However, preparing accurate nontrivial initial states for these simulations is challenging. Classical Euclidean-time Monte-Carlo methods provide a wealth of information about states of interest to quantum simulations. Thus, it is desirable to facilitate state preparation on quantum simulators using this information. To this end, we present a fully classical pipeline for generating efficient quantum circuits for preparing the ground state of an interacting scalar field theory in $1+1$ dimensions. The first element of this pipeline is a variational Ansatz family based on the stellar hierarchy for bosonic quantum systems. The second element of this pipeline is the classical moment-optimization procedure that augments the standard variational energy minimization by penalizing deviations in selected sets of ground-state correlation functions (i.e., moments). The values of ground-state moments are sourced from classical Euclidean methods. The resulting states yield comparable ground-state energy estimates but exhibit distinct correlations and local non-Gaussianity. The third element of this pipeline is translating the moment-optimized Ansatz into an efficient quantum circuit with an asymptotic cost that is polynomial in system size. This work opens the way to systematically applying classically obtained knowledge of states to prepare accurate initial states in quantum field theories of interest in nature.

New threshold measurements for $\gamma p\to pJ/\psi \to p({\mu }^{+}{\mu }^{-})$ by 007 and ${\gamma }^{*}p\to pJ/\psi \to p(e^{+}{e}^{-})$ by CLAS12 allow us to extend the previous phenomenological determination of the $\mathrm{J}/\psi$-proton scattering length, ${\alpha }_{J/\psi p}$, using GlueX threshold data for $\gamma p\to pJ/\psi \to p(e^{+}{e}^{-})$. The agreement between all three $\mathrm{J}/\psi$ datasets shows no indication of systematic differences between methodologies. Furthermore, perturbative QCD predictions support the phenomenological determination of heavy vector meson-nucleon scattering lengths. The role of the nucleon form factor, $F_N$, is discussed, and a possible correction to the phenomenological scattering length for heavy vector meson photoproduction is calculated using the pole form of $F_N$. Upcoming J-PARC threshold measurements of the reaction ${\pi }^{-}p\to nJ/\psi \to n(l^{+}{l}^{-})$ will help to evaluate the possible role of heavy pentaquark, $P_c$, states in low-energy $J/\psi$ production and the effects caused by the nucleon form factors.

The collinear and transverse-momentum-dependent jet fragmentation function and the radial profile for $B^{\pm }$ mesons in jets are measured. The $B^{\pm }$ mesons are reconstructed through the $J/\psi (\to {\mu }^{+}{\mu }^{-})K^{\pm }$ decay channel using proton-proton collision data collected during 2016–2018 with the LHCb detector at a center-of-mass (c.m.) energy of $\sqrt{s}=13\mathrm{TeV}$, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. The results complement recent measurements of jet fragmentation functions for heavy-flavor hadrons and suggest a growing contribution of gluon fragmentation to $B^{\pm }$ mesons as the jet transverse momentum increases.

Regular black holes and horizonless black hole mimickers offer mathematically consistent alternatives to address the challenges posed by standard black holes. However, the formation mechanism of these alternative objects is still largely unclear and constitutes a significant open problem since understanding their dynamical formation represents a first step to assess their existence. We here investigate, for the first time and without invoking higher-curvature corrections, the dynamical formation of a well-known horizonless black hole mimicker, namely, a gravastar. More specifically, starting from the collapse of a uniform dust sphere, as in the case of the Oppenheimer-Snyder collapse, we demonstrate that, under fine-tuned conditions, a gravastar can form from the nucleation and expansion of a de Sitter region with initial zero size at the center of the collapsing sphere. Furthermore, the de Sitter expansion naturally slows down near the Schwarzschild radius, where it meets the collapsing dust surface and gives rise to a static equilibrium. Interestingly, we also find a maximum initial compactness of the collapsing star of $\mathcal{C}=3/8$, above which the collapse to a black hole is inevitable.

The spontaneous breaking of $SO(10)$ via flipped $SU(5)$ to the Standard Model yields a novel scenario in which the superheavy topologically stable grand unified theory (GUT) monopole carrying a single unit ($2\pi /e$) of Dirac magnetic charge emerges from the merger of a confined but topologically distinct monopole-antimonopole pair that are pulled together by a string. The $SO(10)$ breaking via the subgroup $SU(4{)}_c\times SU(2{)}_L\times SU(2{)}_R$, following a similar reasoning, produces a topologically stable monopole that carries two units ($4\pi /e$) of Dirac charge. We explore the cosmological consequences of this scenario by assuming that the monopoles and strings experience a limited number of inflationary $e$-foldings, before reentering the horizon and ultimately forming a network of quasistable strings bounded by monopole-antimonopole pairs. We identify regions of the parameter space that yield an observable number density of the GUT monopole from the collapse of the appropriate string segments. The gravitational waves emitted by these quasistable cosmic strings lie in the Hz to kHz range, which can be tested in a number of proposed and ongoing experiments.

We extensively explore the connections between timelike entanglement and non-Hermitian density matrices in quantum many-body systems. We classify setups where we encounter non-Hermitian density matrices into two types: one is due to causal influences under unitary evolutions, and the other is due to nonunitary evolutions in non-Hermitian systems. We provide various examples of these setups including interacting harmonic oscillators, two dimensional conformal field theories, and holographic dualities. In them, we compute the timelike entanglement entropy and imagitivity, which measures how much density matrices are non-Hermitian. In both two classes, typical holographic examples are given by traversable AdS wormholes. We explain how causal influences in a wormhole dual to a pair of non-Hermitian quantum systems is possible even without interactions between them. We argue that to realize a traversable wormhole we need not only ordinary quantum entanglement but also timelike entanglement.

This paper is a sequel in which we further analyze the recently derived quantum gravity equations which apply in accelerating cosmological spacetimes and whose solutions should be equivalent to all order resummations of the perturbative leading logarithms that appear. In particular, we study their implications concerning the primordial tensor power spectrum and the gravitational force due to a test source.

We compute, for any Rényi index $n$, the exact difference between the mutual Rényi information of a pair of free massless scalars and that of a Maxwell field in $d=4$ dimensions. Using the standard dimensional reduction method in polar coordinates, the problem is mapped to that of a single scalar field in $d=2$ with Dirichlet boundary conditions, which in turn can be conveniently related to the algebra of a chiral current on the full line. This latter identification, which maps operator algebras on an interval to two-interval operator algebras, yields exact results that clarify the structure of the long-distance, perturbative operator product expansion of the mutual information. We find that this series has a finite radius of convergence only for integer $n>1$, while it becomes only asymptotical for $n=1$ and general noninteger values of $n$.

The group-theoretic approach is used to construct exact solutions to perfect fluid equations invariant under the Schrödinger group, or the $\ell$-conformal Galilei group, or the Lifshitz group. In each respective case, the velocity vector field looks similar to the Bjorken flow. It is shown that one can reach an arbitrarily high density (and hence pressure) for a short period of time by adjusting the value of $\ell$ and other free parameters available.

We study rocket-driven Penrose extraction in the test-particle limit on a fixed Kerr background for equatorial prograde flybys under explicit steering prescriptions. A spacecraft ejects exhaust inside the ergosphere; when the exhaust attains negative Killing energy, the remaining spacecraft gains energy by 4-momentum conservation. Across 320,000 simulated trajectories spanning black hole spin, exhaust velocity, and orbital parameters, extraction with escape is rare in broad parameter scans (at most $\sim 1\%$) and requires high spin ($a/M\gtrsim 0.89$), highly relativistic exhaust ($v_e\gtrsim 0.91c$), and finely tuned initial conditions. Under optimal tuning the success rate reaches $\sim 70\%$ at $a/M=0.95$. For representative escape trajectories, a single periapsis impulse is more propellant-efficient than the continuous-thrust controllers studied here. All quoted thresholds are empirical and specific to the orbit family, prior, and steering protocol studied.

We investigate the properties of low angular momentum, inviscid, advective accretion flows in a generic static and spherically symmetric spacetime that incorporates higher-order corrections up to the fourth order in $1/r$. Employing this metric, we self-consistently solve the relativistic hydrodynamical equations and obtain the family of global transonic accretion solutions (O, A, W, and I types) by means of the spacetime parameters $(\delta ,\eta ,\beta )$ and the flow parameters (specific energy $\mathcal{E}$ and angular momentum $\lambda$). Our analysis reveals that the accretion flow possesses either single or multiple critical points depending on these input parameters. We delineate the regions of the $\delta -\lambda$ and $\lambda -ℰ$ parameter spaces that admits solutions with multiple critical points and demonstrate how these regions evolve with increasing spacetime parameter $\delta$. Furthermore, while connecting the spacetime geometry with observable signatures, we compute the spectral energy distribution (SED) from thermal bremsstrahlung emission and observe that increasing $\delta$ enhances the SED relative to the Schwarzschild case. Finally, we find that global transonic solutions harboring inner critical points (I types) yield more luminous power than those with only outer critical points (O and A types).

We present SEOB-TML, an enhanced effective-one-body (EOB) framework for the test-mass limit, optimized for quasicircular, spin-aligned binary black holes. On the dynamical side, we introduce a quadrupole-factorized (Q-factorized) prescription that maps the total energy flux—including horizon absorption—onto a single (2, 2) mode baseline. This approach effectively captures higher-order multipole contributions without explicit mode summation, while simultaneously leading to a dramatic reduction in fractional flux errors. To ensure a smooth transition to the postmerger stage, we replace traditional next-to-quasicircular corrections with a phenomenological Ansatz, enabling a flexible, mode-dependent attachment prescription. For the merger-ringdown stage, we utilize quasinormal mode coefficients extracted from numerical waveforms via qnmfinder to explicitly model mode-mixing effects. These enhancements lead to a substantial reduction in residuals, capturing the complex physical modulations prominent in retrograde configurations. Additionally, we implement the (2, 0) mode across the full waveform, further extending the model’s physical coverage and accuracy. Overall, our framework generates highly accurate late inspiral-merger-ringdown waveforms for extreme-mass-ratio systems, significantly reducing dephasing and improving the near-merger reconstruction. We demonstrate the performance of SEOB-TML against the current state-of-the-art SEOBNRv5HM model, highlighting how our specialized developments extend the reliability of the EOB framework into the test-mass limit.

We consider the optical appearance of a nonsingular, spherically symmetric black hole from Eddington-inspired Born-Infeld gravity coupled to anisotropic fluids. Such a black hole has a single (external) horizon located very near the Schwarzschild radius, $r_h=2M$, while its surface of unstable bound geodesics (photon sphere) is located at a moderately shortened radius than its Schwarzschild counterpart. Relying on a geometrically and optically thin accretion disk with a monochromatic emission described by suitable adaptations of standard unbound profiles previously employed in the literature, we generate images of this solution, which displays relevant modifications to the typical photon ring and central brightness depression features found in black hole images. In this sense, we fit the width of the two first photon rings in order to reconstruct the Lyapunov exponent of nearly bound geodesics characterizing the theoretical ratio of successive rings. Such an exponent is tightly attached to observational features of photon rings such as their relative intensities in time-averaged images and the time-scale of hot-spots. Our results point out that nonsingular black holes of this type are hard to distinguish from their Schwarzschild counterparts using this method alone, since the theoretical, numerical, disk-modeling, and observational uncertainties are too entangled with one another to allow a neat distinction of such an exponent. It also points to the need of incorporating dynamical settings such as hot spots or quasinormal modes from gravitational wave ringdowns as a way to circumvent such difficulties.

In this paper, we present 52 new numerical-relativity (NR) simulations of black-hole–neutron-star (BHNS) mergers and employ the data to inform teobresums-dalí: a multipolar effective-one-body model also including precession and eccentricity. Our simulations target quasicircular mergers and the parameter space region characterized by significant tidal disruption of the star. Convergent gravitational waveforms are produced with a detailed error budget after extensive numerical tests. We study in detail the multipolar amplitude hierarchy and identify a characteristic tidal signature in the $(\ell ,m)=(2,0)$, and (3, 0) modes. We also develop new NR-informed models for the remnant black hole and for the recoil velocity. The numerical data are then used to inform next-to-quasicircular corrections and the ringdown of teobresums-dalí for BHNS mergers. We show an overall order of magnitude improvement in the waveform’s amplitude at merger and more consistent multipoles over our older teobresums-giotto for BHNS mergers. teobresums-dalí is further validated with a new 12-orbit precessing simulation, showing phase and relative amplitude differences below $\sim 0.5$ (rad) throughout the inspiral. The computed mismatches including all the modes lie at the 1% level for low inclinations. Finally, we demonstrate for the first time that teobresums-dalí can produce robust waveforms with both eccentricity and precession, and use the model to identify the most urgent BHNS mergers to simulate for waveform development. Our new numerical data are publicly released as part of the CoRe database.

A set of effective equations for the gauge-invariant gravitational perturbations in the interior of a spherically symmetric, nonrotating black hole is derived within the framework of hybrid loop quantum cosmology. The quantum zero mode of the Hamiltonian constraint, obtained from a perturbative gauge-invariant canonical analysis, is explicitly imposed on a class of quantum states whose wave functions factorize into a background and a perturbative part, related through a geometric relational variable. These states naturally describe regimes with small perturbative backreaction and lead to an effective Hamiltonian and associated dynamics for the perturbations. The resulting equations take the form of Regge-Wheeler equations modified by expectation values of the quantum black hole geometry, providing a clear characterization of quantum corrections to the classical description of the black hole interior. This framework opens the way to investigating hybrid loop quantum gravity effects in the propagation of gravitational waves.

Uniformly accelerated black holes provide a controlled setting to isolate how translatory acceleration and conical defects modify photon dynamics and observable optics. We analyze null geodesics in the subextremal static C-metric, describing an accelerated Schwarzschild black hole pulled by a cosmic string/strut, and we keep the conicity parameter explicit throughout. By using dimensionless variables and a Mino-type parametrization, the conformal Hamilton-Jacobi equation separates and both the radial and polar sectors reduce to Biermann-Weierstrass form, yielding compact closed solutions in terms of Weierstrass elliptic functions. This framework enables a systematic classification of photon trajectories, exhibits the loss of equatorial symmetry for nonzero acceleration via a fixed photon cone of constant-latitude null motion, and identifies a unique spherical photon surface shared by all latitudes. On the observational side, using the tetrad screen map, the circular shadow boundary follows transparently from the photon surface condition. We highlight the explicit cancellation of the conicity parameter and discuss that the angular radius depends on the acceleration and the observer’s position; however, it is independent of the observer’s inclination and of the conicity (because of the string tension). For nonstatic observers, a local Lorentz boost preserves circularity while changing the apparent angular size through aberration. We describe an algebraic inversion that infers the acceleration from a single shadow radius measurement once the mass-distance scale is fixed. Moreover, we derive closed expressions for the photon orbital frequency and Lyapunov exponent, providing eikonal quasinormal mode estimates. These results supply a fully analytic toolkit for ray tracing and parameter inference in accelerated black hole spacetimes, and clarify which observables are (and are not) sensitive to conical defects.

We extend previous conduction-based analogies between ice growth in a lake and cosmological expansion by incorporating buoyancy-driven heat transport. Reformulating the Stefan problem with both conductive and convective fluxes yields an evolution equation for the ice thickness $s(t)$ that is structurally analogous to the Friedmann equations for the cosmological scale factor $a(t)$. Beyond reproducing radiation-, matter-, and curvaturelike behaviors, we introduce a reduced description of convection in which the vertically integrated heat flux reaching the moving ice-water interface is modeled as a power-law function of the instantaneous liquid-layer thickness, generating two additional effective contributions. The first is a constant term, directly analogous to a cosmological constant, arising from the persistence of buoyancy-driven transport under geometric confinement. The second is an $s^{-1}$ contribution originating from the coupling between the moving ice boundary and the convective boundary layer. This term reflects the specific reduced flux-height ansatz adopted, rather than a universal physical prediction. When expressed in Friedmann-like cosmological form, this term entails a fluid with negative energy density and equation-of-state parameter $w=-2/3$. In cosmology this term may be an effective one associated to a network of domain walls made of exotic energy/matter, but it might also arise from an energy exchange between cosmological components. Overall, the results should be interpreted as a structural analogy between evolution equations, showing how nonlinear transport mechanisms in a classical moving-boundary problem can reproduce the hierarchy of scaling terms familiar from cosmology within a reduced and analytically tractable framework.

The two-point correlation function (2PCF) is a cornerstone of precision cosmology, yet its estimation from imaging surveys is vulnerable to contamination and incompleteness arising from imperfect target selection and pipeline-level inclusion decisions. In practice, the scientific target is a physically defined population (e.g., galaxies in a redshift or luminosity range), while the working catalog is constructed from noisy measurements and selection cuts, leading to mismatches between true and observed inclusion. These errors are rarely spatially uniform: they correlate with survey depth, observing conditions, and foreground structure, and can imprint spurious large-scale power or suppress the true clustering signal. High-resolution, high-SNR spectroscopic samples provide gold-standard inclusion in the target population, but are typically available for only a small subset of objects. We introduce a prediction-powered Landy-Szalay (PP-LS) estimator that combines noisy inclusion labels over the full catalog with exact labels on a small spectroscopic subset, while preserving the standard random-catalog normalization that corrects for survey geometry and selection. PP-LS debiases pair counts through residual-based, design-weighted correction terms computed only on the labeled subset, requiring no probability calibration, no known misclassification rates or class priors, no explicit spatial model of contamination, nor forward modeling of the systematics. Under simple random sampling of the labeled subset, we establish recovery of the oracle (true-label) Landy-Szalay pair counts and hence consistency for the target 2PCF. In controlled simulations with clustered and spatially structured contaminants, PP-LS removes the bias of naïve catalog-level estimators while achieving substantially lower variance than spectroscopic-only clustering. The result is a statistically principled, computationally lightweight estimator that integrates directly with standard pair-counting pipelines and supports robust clustering inference in next-generation surveys.