The interplay between toric Calabi-Yau 3-folds, cluster integrable systems, and 5-dimensional quantum field theories has proved fruitful. We extend this framework to generalized toric polygons (GTPs) and show that their integrable systems arise from refined birational transformations of known cluster integrable systems acting on the Casimirs and Hamiltonians as well as the Poisson structure and spectral curves. We argue that these transformations are realized as Hanany-Witten transitions producing $(p,q)$ 5-brane webs dual to GTPs. We show that the resulting $5D$ $\mathcal{N}=1$ theory is obtained by Higgsing a higher-rank theory whose associated toric Calabi-Yau has a toric diagram of the same shape as the GTP.

We investigate primordial black hole (PBH) formation in a cosmological background with bulk viscosity. Using numerical simulations, we determine the collapse threshold and the resulting PBH mass. We find that the critical threshold ${\mu }_c$ retains a dependence on the equation-of-state parameter $w$ similar to that in the inviscid case, but is enhanced by an amount comparable to the bulk-viscosity strength $\epsilon$. For fixed $w$, the increase in ${\mu }_c$ is approximately linear in $\epsilon$. By fitting the standard critical-scaling law for near-threshold collapse, we find that the bulk viscosity leads to an enhancement in the resulting PBH mass. These results indicate that bulk viscosity can systematically modify both the PBH threshold and PBH mass scaling law in the early Universe.

In this paper, we investigate the long range gravitational effect of curvature-scalar field nonminimal coupling in the form of $\xi R{\varphi }^2$, in the perturbative quantum gravity framework. Such coupling is most naturally motivated from the renormalization of a scalar field theory with a quartic self interaction in a curved spacetime background. This coupling results in two scalar-$n$ graviton vertices which contain no explicit momenta of the scalar, qualitatively different from the usual, e.g., $\kappa h^{\mu \nu }{T}_{\mu \nu }$-type minimal matter-graviton vertices. Assuming the dimensionless coupling parameter $\xi$ to be small, we compute the 2-2 scattering Feynman amplitudes between such scalars up to $\mathcal{O}(G^2\xi )$. From the nonrelativistic limit of these amplitudes, we compute the corresponding long range gravitational potential. There exists no tree level contribution $(\mathcal{O}(\xi G))$ here, and hence the one loop $\mathcal{O}(G^2\xi )$ result is leading. Recently, the effect of a cosmological constant in such nonminimal interaction and the subsequent gravitational potential was computed. In this work, we take the cosmological constant to be vanishing. The resulting potential is found to have $r^{-4}$ leading behavior. We further extend these results for scalar-massive spin-1 and massive spin-$1/2$ scattering. Spin and polarization dependence of the two body potential have been explicitly demonstrated. We discuss some possible physical implications of these results.

We have recently shown that a natural way to implement the Wilsonian paradigm in gauge theories is through the introduction of a “spectral cutoff,” a cut on the eigenvalues of the covariant Laplacian, pointing out that this provides the route toward the renormalization group (RG) construction. Here, we apply this idea to quantum gravity, resorting to two realizations of the spectral running cutoff: “hard” and “smooth.” We derive the RG equations for the Newton and cosmological constant and find the RG pattern of the asymptotic safety scenario, with a non-Gaussian UV-attractive fixed point.

We examine, in the Landau background gauge, the effective action of a quantum theory of gravitational and matter fields. We analyze the Becchi-Rouet-Stora-Tyutin invariance of this theory and study the Ward identities which implement the symmetry of the background effective action. The off-shell and on-shell counterterm Lagrangians are explicitly calculated in this gauge at one-loop order. We argue that the matter self-energy in the Landau background gauge, which is finite to this order, may be finite also at higher loops.

Accurate models of merger remnants are increasingly important for gravitational-wave science, including precision tests of gravity with ringdown, inference of black-hole populations, and modeling hierarchical mergers. For eccentric binaries, remnant mass, spin, and recoil carry nontrivial imprints of eccentricity that are both physically informative and more challenging to model, yet remain less developed than in the quasicircular case. We present two new models trained on numerical-relativity (NR) simulations of unequal-mass, nonspinning eccentric binary black holes: NRSurE_q4NoSpin_Remnant, which predicts remnant properties, and NRSurE_q4NoSpin_Dynamics, a time-domain surrogate for the evolution of eccentricity and mean anomaly. Both models are trained on NR simulations over a three-dimensional parameter space with mass ratios $q\le 4$, eccentricity $e<0.23$, and mean anomaly $\ell \in [0,2\pi )$ radians, where both $e$ and $\ell$ are defined at $t=-1000M$ relative to peak amplitude and $M$ is the total mass. We highlight some applications, including the phenomenological impact of eccentricity on remnant properties and the enhancement or suppression of recoil. We also provide error estimates for all modeled quantities, supporting reliable use in current and future gravitational-wave parameter-estimation analyses. Both models will be made available through open-source codes.

In this paper, we employ the open quantum system framework with the influence functional formalism to nonperturbatively analyze the response of an Unruh-DeWitt detector modeled as a harmonic oscillator which interacts with a massless scalar field in impulsive plane wave spacetimes. Subtracting the Minkowski results, we obtain the expectation values for $⟨Q^2⟩$, $⟨P^2⟩$, and $⟨\{Q,P\}⟩$, along with transition probabilities $P_{0\to 1}$ from ground state to the first excited state of the detector due to the influence of the wave. Explicit calculations are performed for both a pure gravitational wave (vanishing Ricci tensor) and a null electromagnetic wave (vanishing Weyl tensor). In both scenarios, the wave suppresses excitation transitions. Since our approach is nonperturbative, we are able to consider cases with both weak and strong coupling constants.

The Teukolsky equation possesses discrete symmetries that constrain the properties of black hole perturbations and their quasinormal mode spectrum. In this study, we explore how a class of modifications of the Teukolsky potential can alter the symmetry structure of the equation and break the $m=0$ degeneracy of quasinormal modes. We prove this result in the frequency domain using the master Teukolsky equation and in the time domain via ($2+1$)-dimensional simulations. We also show that the discrete symmetries can be leveraged for a more efficient characterization of the $m=0$ quasinormal modes from time-domain evolutions. As a theory-specific application, we consider the case of higher-derivative theories of gravity, highlighting that time-domain implementations of frequency-domain potentials can give rise to additional nonphysical branches of modes.

We study the conformal scattering of massless scalar waves in Minkowski spacetime. The conformal scattering problem is formulated as a Goursat (characteristic initial value) problem of the physical wave equation in compactified double-null coordinates, including the neighborhood of spatial infinity $i^0$. As null infinities ${\mathcal{I}}^{\pm }$ lie on the domain boundary by construction, asymptotic radiation is directly accessible. We consider three physical scenarios: free wave propagation, scattering off a Pöschl-Teller (PT) potential, and the semilinear $|\varphi {|}^{n-1}\varphi$ wave equation. For multipole numbers $\ell =0$, 1, an explicit stencil, averaging along the spatial direction, yields globally second-order convergent results. For $\ell \ge 2$, an implicit stencil averaging along the temporal direction is required for numerical stability. Although the singular $i^0$ reduces the convergence of the radiation data on ${\mathcal{I}}^{+}$ to first order, Richardson extrapolation enhances the effective convergence rate to approximately 1.5. For PT scattering, our method accurately computes scattering quantities, notably the phase shifts induced by the potential. In the semilinear case, our method captures the physical signatures of a self-defocusing Kerr nonlinearity, including self-phase modulation and spectral broadening. The compactified double-null framework proves to be simple and efficient, suggesting a promising approach to the global evolution of conformal scattering.

We show that higher-curvature Lovelock terms do not restore local cosmic censorship in spherical dust collapse, but instead promote the local visibility of central shell-focusing singularities. On the collapse branch with positive highest-order Lovelock coefficient $c_N$, the highest nonvanishing Lovelock order $N$ controls both the near-singularity collapse and the formation of trapped surfaces. In noncritical dimensions $D-1-2N>0$, the apparent-horizon curve approaches the singularity curve with trapping exponent ${\beta }_N=(D-1)/(D-1-2N)$. Comparing this scale with the first nonvanishing correction $r^{\ell }$ to the singularity curve gives the local-visibility condition $\ell <{\beta }_N$, provided the singularity curve opens outward. Thus, increasing $N$ enlarges the class of inhomogeneous initial data producing outgoing radial null rays from the central singularity. In the critical odd-dimensional branch $D=2N+1$, no apparent horizon forms sufficiently close to the center, so any outward opening of the singularity curve gives local visibility. The locally visible singularities are Królak-strong along the emerging null rays, with Tipler strength reached at threshold. For bound and unbound collapse, the noncritical exponents are unchanged: the energy function modifies the opening of the singularity curve, while in the critical branch it enters the leading terminal collapse velocity.

In the present work, we study the absorption cross section of a Schwarzschild black hole for a massive vector field over arbitrary frequencies. Working in the Frolov-Krtouš-Kubizňák-Santos basis, we show how the conserved flux of the normalized Proca field naturally leads to the usual definitions of the absorption cross section in terms of the reflection and transmission coefficients. We then numerically compute these quantities over arbitrary frequencies. In contrast to the massless (photon) case, massive vector bosons exhibit new features arising from the field mass. In particular, the mass term introduces a longitudinal degree of freedom in addition to the transverse modes. Furthermore, it leads to a scalar-type branch in the even-parity transverse modes, thereby breaking the usual degeneracy with the odd-parity sector found in the massless case. We illustrate how these characteristics manifest themselves in the transmission and absorption spectrum. Given the recent developments in the study of ultralight bosonic fields in black hole spacetimes, the present analysis of the transmission properties of massive vector bosons bears particular significance.

We analytically determine the leading backreaction of a spherically symmetric massive complex scalar quasibound state (with mass $\mu$) on a Schwarzschild black hole with (initial) gravitational radius $r_0$. Working in the small-coupling regime, $r_0\mu \ll 1$, we evaluate the stress-energy tensor of the fundamental scalar $s$ wave and solve the Einstein equations through quadratic order in its amplitude in ingoing Eddington-Finkelstein coordinates. We also determine the small-mass quasiresonant frequency of the fundamental $s$ wave analytically by matched asymptotic expansions and validate it numerically using Leaver’s method. Unlike steady-state treatments, the calculation retains the exponential decay of the quasibound state. We obtain explicit expressions for the metric perturbations and Misner-Sharp mass and derive the evolution of the future outer trapping horizon. The black-hole mass grows monotonically with the decaying horizon flux and saturates when the finite scalar cloud has been absorbed, with the decrease of the cloud mass exactly balancing the horizon growth at the perturbative order considered. We also determine the domain in which the scalar small-coupling approximation and the gravitational perturbative expansion are simultaneously valid.

Next-generation gravitational-wave detectors, such as LISA, the Einstein Telescope, and Cosmic Explorer, will require accurate and efficient models of long-lived black hole binary signals, including those with significant eccentricity. A challenge for eccentric effective-one-body (EOB) models is the cost of resolving rapidly oscillating orbital dynamics over the inspiral, particularly for low-mass and large-mass-ratio systems. We address this by recasting the nonspinning eccentric effective-one-body equations of motion in terms of osculating orbital elements and then applying near-identity averaging transformations to eliminate the fast orbital-timescale structure during the inspiral. Each order in this procedure suppresses the oscillatory behavior by one factor of the ratio of orbital to radiation-reaction timescales. The resulting averaged dynamics are evolved on the radiation-reaction timescale, and then, the system is mapped back to the full EOB dynamics for the final transition to plunge. This reduces the cost of the inspiral dynamics by up to 2 orders of magnitude, eliminating this as the primary bottleneck for long waveforms. The overall waveform-generation speedup spans $1.5-8\times$, motivating the development of more efficient waveform-generation methods. We also validate the accuracy of the method by comparing waveforms generated from the averaged and full effective-one-body dynamics across a broad region of parameter space for moderate to large eccentricities. Carrying out this averaging procedure to next-to-next-to-leading order is needed to accurately model comparable-mass binaries, yielding mismatches $\le 8.05\times {10}^{-5}$. These results establish near-identity averaging as a practical route to efficient eccentric effective-one-body inspirals and provide a foundation for further extensions to low-eccentricity and spinning waveform models.

The annihilation of dark matter (DM) particles is expected to produce Standard Model particles, providing a potential indirect signature of DM. The clumpy substructure of DM haloes amplifies the expected annihilation signal, an effect commonly quantified by the subhalo boost factor. Standard semianalytic models usually treat this boost as a universal function of host-halo mass, neglecting systematic variations induced by the large-scale environment. In this work, we extend this framework by incorporating the influence of the cosmic-web on subhalo populations. Using simulation-calibrated, environment-dependent ratios for host-halo concentrations, the subhalo mass function, and the internal-structure proxies of subhalos based on the $V_{\max }–R_{\max }$ relation, we compute environment-conditioned boost predictions for haloes residing in filaments, walls, and voids. Our main result is the boost factor at fixed host-halo mass, expressed relative to the cosmic-mean prediction, $B(M,\mathrm{env})/B_{\mathrm{CM}}(M)$. We find a clear environmental modulation: in the fiducial distance-dependent model, filament haloes show a mass-dependent transition from a $\sim 15\%$ suppression at the low-mass end to a modest enhancement of $\sim 12\%$ for massive hosts, wall haloes remain intermediate, while void haloes stay suppressed by roughly 30%–33% across the explored host-mass range. These results should be interpreted as deterministic model predictions obtained by propagating environment-dependent ingredient ratios through two standard semianalytic boost frameworks. We provide an environment-aware prescription for subhalo boosts, together with modular environmental corrections that may also be useful in indirect-detection forecasts, strong-lensing mass modeling, and related halo-population applications.

We explore the capture of neutrinos and photons in the cosmic neutrino and photon background by primordial black holes (PBHs). We model this phenomenon as a gravitational interaction that effectively modifies the continuity equations for radiation and PBH densities and the cosmic expansion history. We find that the observability of this modified cosmic history and background densities is highly sensitive to PBH mass, and only extraordinarily massive PBHs would leave observable trace on the temperature and E-mode polarization of the cosmic microwave background (CMB). Specifically, Planck data restrict PBH abundance to $f_{\mathrm{pbh}}\lesssim {10}^{-1}$ for PBH masses above ${10}^{15}{M}_{\odot }$, getting considerably tighter for higher masses. We expect substantial improvement as high-resolution measurements of larger CMB multipoles become available. A future cosmic-variance-limited experiment, with ${\ell }_{\max }=7000$, would set $f_{\mathrm{pbh}}\lesssim {10}^{-1}–8\times {10}^{-5}$ (for the fiducial $\mathrm{\Lambda }\mathrm{CDM}$ cosmology) across ${10}^{13}–{10}^{18}{M}_{\odot }$. These constraints would be comparable to the current limits at the high-mass end of the spectrum [Carr et al. Riv. Nuovo Cimento 49, 225 (2026)]. The gravitational interaction of PBHs with the cosmic background radiation and its imprints on CMB would, thus, provide an independent complementary probe of extraordinarily massive PBH abundance.

Gravitational-wave searches rely on a combination of methods, including matched filtering, coherent analyses, and more recent machine-learning–based pipelines. For compact binary coalescences—where signals originate from the relativistic dynamics of compact objects—matched filtering remains a central element, but its computational cost will increase substantially with the data volumes and parameter-space coverage required by next-generation interferometers such as the Einstein Telescope. Developing complementary strategies that reduce computational load while preserving detection performance is therefore essential. We investigate a hybrid approach that combines matched-filtering concepts with convolutional neural networks, enabling efficient signal searches without relying on the usual ${\chi }^2$ rejection test. Using simulated datasets that include injected signals in Gaussian noise, transient noise, and physical effects not represented in the template bank—such as eccentricity, precession and higher-order modes—we show that the method achieves a detection efficiency comparable to or better than a standard matched-filtering search while offering a more resource-efficient pipeline in all the cases where the physics included in the signals were not represented in the template bank or when glitches were affecting the data. Conversely, the analysis also reveals some loss of detection capability for standard binary neutron star and binary black hole searches in pure Gaussian noise. These results indicate that deep-learning–assisted searches can support sustainable gravitational-wave data analysis in future detector eras.

Measurements of cosmic-ray proton and helium spectra below the knee show deviations from simple power laws, including multi-TeV structures. A possible explanation is that one or a few nearby sources contribute an additional component to the local spectrum. However, a previous study shows that a dominant local contribution is statistically unlikely under a homogeneous diffusion model. In this work, we investigate how this probability changes if cosmic rays experience inefficient transport near their sources, motivated by observations of extended $\gamma$-ray emission around Galactic accelerators. We derive a series Green’s function that enables fast calculations of the particle distribution in this scenario, making Monte Carlo calculations for Galactic source populations feasible. The inner slow-diffusion region delays escape and redistributes the arriving particles in time and energy. In Monte Carlo realizations, the probability that the strongest local source becomes comparable to the background at 10 TeV increases from about 0.4% in homogeneous diffusion to 1.7%–2.2% in the two-zone models. Thus inhibited near-source transport weakens, but does not remove, the statistical difficulty. We then examine cataloged nearby candidate supernova remnants and show that a 10 TeV feature can be reproduced only with additional assumptions, especially a harder local injection spectrum and a favorable diffusion coefficient. The predicted contribution of a given source changes strongly among different particle transport models. Therefore, the local-source interpretations are plausible but highly model dependent and require independent constraints on source injection history, particle transport mechanisms, and local interstellar turbulence.

We study neutrino, muon, and gamma-ray fluxes in extraterrestrial environments in our Solar System via semianalytical estimates and Monte Carlo simulations. In sites with negligible atmosphere, we find a strong reduction in the cosmic-ray-induced neutrino and muon fluxes relative to their intensities on Earth. Neutrinos with energies between 50 MeV and 100 TeV show particularly strong suppression, by as much as ${10}^3$, even at shallow depths. The solar neutrino suppression increases as the square of the site’s distance from the Sun. Natural radiation due to nuclear decay is also expected to be lower in many of these locations and may be reduced to effectively negligible levels in liquid water environments. The sites satisfying these characteristics represent an opportunity for greatly extending the physics reach of underground searches in fundamental physics, such as searches for weakly interacting massive particle (WIMP) dark matter, neutrinoless double-beta decay, the diffuse supernova neutrinos, and neutrinos from nearby supernova. As a potential near-term target, we propose a measurement of muon and gamma-ray fluxes in an accessible underground lunar site such as the Mare Tranquillitatis pit to perform a first measurement of the prompt component in cosmic-ray-induced particle production, and to constrain lunar evolution models. Although the focus of this work is on fundamental physics, the finding of this work—that the existence of an atmosphere in a planet enhances cosmic-ray-induced radiation in its underground—could be relevant for a broader range of sciences, such as radiobiology deep underground and searches for extraterrestrial life.

We compute the next-to-leading order corrections to the radiative return process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ using a dispersive representation of the pion form factor for the calculation of loop integrals. We compare our results with those of the factorized scalar QED approach, as well as with previous predictions obtained by us in the generalized vector meson dominance model. We show the numerical impact of the structure-dependent corrections on various observables of interest for radiative return experiments at flavor factories. Following recent input from the literature, we include in our calculation also corrections due to neutral pseudoscalar poles, and we provide a first estimate of such contributions. We also investigate additional mechanisms contributing to final-state radiation at center-of-mass energies around the $\varphi$-meson resonance, such as radiative $\varphi$ decays, presenting numerical results that are relevant for the KLOE experiment. These novel features are implemented in the Monte Carlo event generator babayaga@nlo, which can now be used to evaluate the impact of the modeling of pion-photon interaction in radiative return measurements.

We show that there exists a theoretically well-motivated Higgs sector in which the conventional heavy-Higgs production mechanisms are suppressed. In this limit, the $b$-associated production channel assumes the role of the primary production mechanism. We demonstrate that the democratic three Higgs-doublet model (3HDM) provides a viable beyond the SM framework in which this limit can be realized. We further show that existing $b$-associated searches provide the most sensitive LHC probe of this 3HDM scenario in the up-phobic limit and derive the corresponding constraints on its parameter space. We also present projections for future collider searches, demonstrating their potential to probe further regions of the model’s up-phobic parameter space.