The standard formula, due to Spiegel, for the smoothing of temperature fluctuations by radiative transfer is unstable in relativity. This is due to the fact that Spiegel neglected the transit time of light, thereby allowing the transport coefficients to move outside the convex geometry compatible with causality (the “hydrohedron”). Here, we fix this pathology. First, we prove that the linearized radiative transfer equations are causal and covariantly stable by construction. Then, we repeat Spiegel’s calculation accounting for the finite speed of photons. We find that the full transfer problem can be solved analytically. All the infinite (exact) transport coefficients arising from it fall inside the hydrohedron. Our analysis also accounts for isotropic scattering.

We establish that regular black holes can form from gravitational collapse in all $D\ge 5$. Our model builds on a recent construction that realized regular black holes as exact solutions to purely gravitational theories that incorporate an infinite tower of higher curvature corrections [P. Bueno et al., Regular black holes from pure gravity, Phys. Lett. B 861, 139260 (2025).]. We identify a two-dimensional Horndeski theory that captures the spherically symmetric dynamics of the theories in question and use this to prove a Birkhoff theorem and obtain the generalized Israel junction conditions. Armed with these tools, we consider the collapse of thin shells of pressureless matter, showing that this leads generically to the formation of regular black holes. The interior dynamics we uncover is intricate, consisting of shell bounces and white hole explosions into a new universe. The result is that regular black holes are the unique spherically symmetric solutions of the corresponding theories and also the end point of gravitational collapse of matter. Along the way, we establish evidence for a solution-independent upper bound on the curvature, suggestive of Markov’s limiting curvature hypothesis.

The cosmic calibration tension is a $>5\sigma$ discrepancy between the cosmological distance ladder built from baryonic acoustic oscillations calibrated by the $\mathrm{Planck}/\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) sound horizon ($r_s$) and type Ia supernovae calibrated instead with the SH0ES absolute magnitude, assuming the distance-duality relationship holds. In this work, we emphasize the consequences of this tension beyond the value of the Hubble constant $H_0$ and the implications for physics beyond $\mathrm{\Lambda }\mathrm{CDM}$. Of utmost importance, it implies a larger physical matter density ${\omega }_{\mathrm{m}}\equiv {\mathrm{\Omega }}_{\mathrm{m}}{h}^2$, as both the fractional matter density ${\mathrm{\Omega }}_{\mathrm{m}}$ and $h\equiv H_0/100\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$ are well constrained from late-time data. New physics in the prerecombination era must thus be able to decrease $r_s$ while either reducing the value of ${\mathrm{\Omega }}_{\mathrm{m}}$ or increasing the value of ${\omega }_{\mathrm{m}}$. Assuming a $\mathrm{\Lambda }\mathrm{CDM}$-like primordial power spectrum, this necessarily results in an increase in the clustering amplitude ${\sigma }_8$. Deviations from $\mathrm{\Lambda }\mathrm{CDM}$ in the late-time expansion history cannot resolve the calibrator tension but can help relax the required shifts to the matter density and ${\sigma }_8$: it is in that sense that a combination of early- and late-time new physics may help alleviate the tension. More precisely, models that modify the prerecombination expansion history can accommodate the increase in ${\omega }_{\mathrm{m}}$ without the need for additional modifications. It is those models which only affect recombination that require additional deviations at late times to be successful. Hence, the cosmic calibration tension points either to a targeted modification of the prerecombination expansion history or to a broader change affecting multiple cosmic epochs.

We study the equation of state of hot and dense hadronic matter using an extended chiral mean field (CMF) model framework where the addition is the inclusion of interactions of thermally excited mesons. This is implemented by calculating the in-medium masses of pseudoscalar and vector mesons, obtained through the explicit chiral symmetry-breaking and vector-interaction terms in the Lagrangian, respectively, prior to applying the mean-field approximation. As a result, the in-medium meson contributions generate a feedback term to the CMF’s equations of motion, which then modifies the equation of state. With this improvement, we quantify the effect on the equation of state of strongly interacting matter through comparisons with state-of-the-art lattice QCD results and other hadronic models like the hadron resonance gas model. We find that the results of the updated hadronic CMF model with an improved meson description (mCMF) provide a better agreement with lattice-QCD data for thermodynamic state variables across a wide range of temperatures and baryon chemical potentials.

Dark matter has been theorized to be charged under its own “dark electromagnetism” (dark-EM). Under this hypothesis, dark matter can behave like a cold collisionless plasma of self-interacting dark matter particles and exhibit plasmalike instabilities with observational consequences. Using the results published in [Phys. Rev. E 105, 035204 (2022)], which studied the degree of slowdown between two interpenetrating $e^{-}{e}^{+}$ plasma clouds due to plasma instabilities, estimates of similar interactions for colliding “dark plasmas” are explored. Comparison with astronomical observations reveals strong new constraints on dark-EM with the dark electromagnetic self-interaction ${\alpha }_D<4\times {10}^{-25}$.

We extend the dust-filament-based model presented in Hervías-Caimapo and Huffenberger [Astrophys. J. 928, 65 (2022)] to produce parity-violating foreground spectra by manipulating the filament orientations relative to the magnetic field. We calibrate our model to observations of the misalignment angle using cross-correlations of Planck and HI 21-cm line data, producing a fiducial model that predicts a ${\mathcal{D}}_{\ell }^{EB}\sim \mathrm{few}\mathrm{\mu }{\mathrm{K}}^2$ dust signal at 353 GHz and where $\sim 56\%$ of filaments have a positive misalignment angle. The main purpose of this model is to be used as dust with nonzero parity-violating emission in forecasting a measurement of cosmic birefringence by upcoming experiments. Here, we also use our fiducial model to assess the impact of dust in measurements of the isotropic cosmic birefringence angle $\beta$ with Planck data by measuring the misalignment angle as a function of scale, as well as directly using our model’s ${\mathcal{D}}_{\ell }^{EB}$ prediction as a template. In both cases, we measure $\beta$ to be consistent within $0.83\sigma$ of the analyses that use the 353 GHz channel of Planck to constrain the filamentary misalignment or that use the commander sky model as a template for the dust ${\mathcal{D}}_{\ell }^{EB}$ spectrum. We attribute this consistency to the extra degrees of freedom introduced by the ad hoc amplitude parameters for the dust parity-violating spectrum, which are capable of absorbing most of the differences between the model and data as long as a reasonable dust model is provided.

Tidal interactions in a coalescing binary neutron star (BNS) or neutron star-black hole (NSBH) system driven by gravitational wave (GW) radiation contain precious information about physics both at extreme density and in the highly relativistic regime. In the late inspiral stage, where the tidal effects are the strongest, finite-frequency or even dynamical corrections to the tidal response become significant. Many previous analyses model the finite-frequency correction through the effective Love number approach, which only accounts for the correction in the radial interaction but ignores the lag in the tidal bulge behind the companion due to the continuous orbital shrinkage. The lag provides a torque between the orbit and the tidal bulge, causing the star’s spin to change over time. We dub the evolving component of the spin the tidal spin, whose dimensionless value can reach 0.03–0.4 depending on how rapidly the background star rotates. We present a relativistic, effective-one-body (EOB) waveform model for BNSs and NSBHs that incorporates the tidal spin, particularly its backreaction to the orbit due to the Newtonian tidal torque and the relativistic orbital hang-up. Beyond the conservative dynamics specified by the EOB Hamiltonian, we also derive the corrections to the dissipative GW radiation due to finite-frequency effects to the first post-Newtonian order. Depending on the star’s background spin, the phase error in the time-domain waveform due to ignoring the tidal spin ranges from 0.3 to 4 radians at the waveform’s peak amplitude. Notably, the difference in the waveforms with and without the tidal spin remarkably resembles the difference between previous effective Love number models and numerical relativity simulations, underscoring the significance of tidal spin in the construction of faithful models. Our model further extends the description of dynamics in the high-background spin regions of the parameter space that are yet to be covered by numerical simulations.

We construct compactifications of type IIB string theory that yield, at leading order in the ${\alpha }^{\prime }$ and $g_s$ expansions, de Sitter vacua of the form envisioned by Kachru et al. We specify explicit Calabi-Yau orientifolds and quantized fluxes for which we derive the four-dimensional effective supergravity theories, incorporating the exact flux superpotential, the nonperturbative superpotential from Euclidean D3-branes, and the Kähler potential at tree level in the string loop expansion but to all orders in ${\alpha }^{\prime }$. Each example includes a Klebanov-Strassler throat region containing a single anti-D3-brane, whose supersymmetry-breaking energy, computed at leading order in ${\alpha }^{\prime }$, causes an uplift to a metastable de Sitter vacuum in which all moduli are stabilized. Finding vacua that demonstrably survive subleading corrections, and in which the quantization conditions are completely understood, is an important open problem for which this work has prepared the foundations.

We advocate a strategy of bootstrapping Feynman integrals from just knowledge of their singular behavior. This approach is complementary to other bootstrap programs, which exploit nonperturbative constraints such as unitarity, or amplitude-level constraints such as gauge invariance. We begin by studying where a Feynman integral can become singular, and the behavior it exhibits near these singularities. We then characterize the space of functions that we expect the integral to evaluate to, in order to formulate an appropriate ansatz. Finally, we derive constraints on where each singularity can appear in this ansatz, and use information about the expansion of the integral around singular points in order to determine the value of all remaining free coefficients. Throughout, we highlight how constraints that have previously only been derived for integrals with generic masses can be extended to integrals involving particles of equal or vanishing mass. We illustrate the effectiveness of this approach by bootstrapping a number of examples, including the four-point double box with a massive internal loop.

We give a general procedure for constructing an extended phase space for Yang-Mills theory at null infinity, capable of handling the asymptotic symmetries and construction of charges responsible for ${\mathrm{sub}}^n$-leading soft theorems at all orders. The procedure is coordinate and gauge-choice independent and can be fed into the calculation of both tree and loop-level soft limits. We find a hierarchy in the extended phase space controlled by the Bernoulli numbers arising in Todd genus computations. We give an example of a calculation at tree level, in radial gauge, where we also uncover recursion relations at all orders for the equations of motion and charges.

In this paper we present a first ab initio calculation of the ${\pi }^0$, $\eta$ and ${\eta }^{\prime }$ transition form factors performed with physical light-quark masses. We provide a complete parametrization of the form factors that includes both single and double-virtual kinematics. Our results are compared with experimental measurements of the form factors in the spacelike region and with the measured two-photon decay widths. In a second step, our parametrizations of the transition form factors are used to compute the dominant pseudoscalar-pole contributions to the hadronic light-by-light scattering in the muon $g-2$. Our final result reads $a_{\mu }^{\mathrm{hlbl},\text{ps-pole}}=(85.1\pm 5.2)\times {10}^{-11}$. Although the pion-pole is dominant, we confirm that, together, the $\eta$ and ${\eta }^{\prime }$ provide roughly half of its contribution.

We investigate the impact of momentum-dependent particle widths and propagators on gauge and Higgs bosons and the top quark within the Standard Model (SM) and its effective field theory (SMEFT) extensions near thresholds. By incorporating self-energy corrections via Dyson resummation, we quantify deviations from the fixed-width approximation and assess their implications for collider observables. While effects on the Higgs boson are negligible and the $W$ boson shows percent-level deviations in reconstructed transverse mass distributions, the top quark exhibits significant sensitivity near its mass threshold. Future lepton colliders, e.g., electron-positron machines or muon colliders, can offer sensitivity to these effects, enabling constraints on SMEFT Wilson coefficients. We perform a representative case study for the precision frontier available with a staged future muon collider. Our results highlight that momentum dependencies can provide additional sensitivity at precision-era experiments, enhancing the potential for discovering new physics there.

The amplitude of the baryon signature in galaxy clustering depends on the cosmological baryon fraction. We consider two ways to isolate this signal in galaxy redshift surveys. First, we extend standard template-based baryon acoustic oscillation (BAO) models to include the amplitude of the baryonic signature by splitting the transfer function into baryon and cold dark matter components with freely varying proportions. Second, we include the amplitude of the split as an extra parameter in effective field theory of large scale structure (EFT) models of the full galaxy clustering signal. We find similar results from both approaches. For the Baryon Oscillation Spectroscopic Survey (BOSS) data we find $f_b\equiv {\mathrm{\Omega }}_b/({\mathrm{\Omega }}_b+{\mathrm{\Omega }}_c)=0.173\pm 0.027$ for template fits postreconstruction, $f_b=0.153\pm 0.029$ for template fits prereconstruction, and $f_b=0.154\pm 0.022$ for EFT fits, with an estimated systematic error of 0.013 for all three methods. Using reconstruction only produces a marginal improvement for these measurements. Although significantly weaker than constraints on $f_b$ from the cosmic microwave background, these measurements rely on very simple physics and, in particular, are independent of the sound horizon. In a companion paper we show how they can be used, together with big bang nucleosynthesis measurements of the physical baryon density and geometrical measurements of the matter density from the Alcock-Paczynski effect, to constrain the Hubble parameter. While the constraints on $H_0$ based on density measurements from BOSS are relatively weak, measurements from DESI and Euclid will lead to errors on $H_0$ that can differentiate the cosmological and distance ladder $H_0$ measurements.

Violating the slow-roll regime during the final stages of inflation can significantly enhance curvature perturbations, a scenario often invoked in models producing primordial black holes and small-scale scalar induced gravitational waves. When perturbations are enhanced, one approaches the regime in which tree-level computations are insufficient, and nonlinear corrections may become relevant. In this work, we conduct lattice simulations of ultraslow-roll (USR) dynamics to investigate the significance of nonlinear effects, both in terms of backreaction on the background and in the evolution of perturbations. Our systematic study of various USR potentials reveals that nonlinear corrections are significant when the tree-level curvature power spectrum peaks at ${\mathcal{P}}_{\zeta }^{\max }=\mathcal{O}({10}^{-3})-\mathcal{O}({10}^{-2})$, with $5\%–20\%$ corrections. Larger enhancements yield even greater differences. We find a simple universal relation between simulation and tree-level quantities $\dot{\varphi }={\dot{\varphi }}_{\mathrm{tree}}(1+\sqrt{{\mathcal{P}}_{\zeta ,\text{tree}}^{\max }})$ at the end of the USR phase, which is valid in all cases we consider. Additionally, we explore how nonlinear interactions during the USR phase affect the clustering and non-Gaussianity of scalar fluctuations, crucial for understanding the phenomenological consequences of USR, such as scalar-induced gravitational waves and primordial black holes. Our findings demonstrate the necessity of going beyond leading order perturbation theory results, through higher-order or nonperturbative computations, to make robust predictions for inflation models exhibiting a USR phase.

Ultralight dark matter (UDM) may manifest itself through oscillating fundamental constants of normal matter. These can be experimentally searched for by implementing two dissimilar oscillators producing a beat between their frequencies and analyzing the beat-frequency time series for the presence of any temporal oscillations. Typically, the time series of such a detector contains contributions from nonstationary noise. In order to reduce the influence of such noise we propose and demonstrate paired detectors: two nominally identical detectors whose signals are synchronously recorded. The cross-spectrum of the two individual beat time series is then analyzed for UDM signatures. This approach permits us to suppress spurious signals appearing in uncorrelated fashion in either detector. We furthermore demonstrate detectors that are based on a vibrational molecular transition, which are advantageous due to their larger sensitivity to oscillations of the nuclear masses. The analysis of 274 hours of data yielded improved bounds for the coupling constants of UDM to nuclear mass and to electron mass in the frequency ranges 10–500 Hz and 10–122 kHz, with improvement factors between 6 and 10. These bounds are currently the strongest. Similar bounds are obtained for the fine-structure constant. The present approach may be generalized to large ensembles of detectors.

The baryonic feedback effect is considered as a possible solution to the so-called $S_8$ tension indicated in cosmic shear cosmology. The baryonic effect is more significant on smaller scales, and it affects the cosmic shear two-point correlation functions (2PCFs) with different scale and redshift dependencies from those of the cosmological parameters. In this paper, we use the Hyper Suprime-Cam Year 3 (HSC-Y3) data to measure the cosmic shear 2PCFs (${\xi }_{\pm }$) down to 0.28 arcminutes, taking full advantage of the high number density of source galaxies in the deep HSC data, to explore a possible signature of the baryonic effect. While the published HSC analysis used the cosmic shear 2PCFs on the angular scales that are sensitive to the matter power spectrum at $k\lesssim 1h{\mathrm{Mpc}}^{-1}$, the smaller-scale HSC cosmic shear signal allows us to probe the signature of the matter power spectrum up to $k\simeq 20h{\mathrm{Mpc}}^{-1}$. Using the accurate emulator of the nonlinear matter power spectrum, darkemulator2, we show that the dark-matter-only model can provide an acceptable fit to the HSC-Y3 2PCFs down to the smallest scales. In other words, we do not find any clear signature of the baryonic effects, or we do not find a systematic shift in the $S_8$ value with the inclusion of the smaller-scale information as would be expected if the baryonic effect were significant. Alternatively, we use a flexible six-parameter model of the baryonic effects, which can lead to both enhancement and suppression in the matter power spectrum compared to the dark-matter-only model, to perform the parameter inference of the HSC-Y3 2PCFs. We find that the small-scale HSC data allow only a fractional suppression of up to 5% in the matter power spectrum at $k\sim 1h{\mathrm{Mpc}}^{-1}$, which is not sufficient to reconcile the $S_8$ tension. Finally, we discuss that ${\xi }_{-}$ on scales smaller than a few arcminutes can be used to monitor characteristic features caused by the baryonic effect if present, while ${\xi }_{\pm }$ with appropriate scale cuts can be used to constrain the cosmological parameters, simultaneously.

We present a simulation-based cosmological analysis using a combination of Gaussian and non-Gaussian statistics of the weak lensing mass (convergence) maps from the first three years of the Dark Energy Survey. We implement the following: (1) second and third moments; (2) wavelet phase harmonics; (3) the scattering transform. Our analysis is fully based on simulations, spans a space of seven $w$ Cold Dark Matter ($w\mathrm{CDM}$) cosmological parameters, and forward models the most relevant sources of systematics inherent in the data: masks, noise variations, clustering of the sources, intrinsic alignments, and shear and redshift calibration. We implement a neural network compression of the summary statistics, and we estimate the parameter posteriors using a simulation-based inference approach. Including and combining different non-Gaussian statistics is a powerful tool that strongly improves constraints over Gaussian statistics (in our case, the second moments); in particular, the figure of merit $(S_8,{\mathrm{\Omega }}_{\mathrm{m}})$ is improved by 70% ($\mathrm{\Lambda }\mathrm{CDM}$) and 90% ($w\mathrm{CDM}$). When all the summary statistics are combined, we achieve a 2% constraint on the amplitude of fluctuations parameter $S_8\equiv {\sigma }_8({\mathrm{\Omega }}_{\mathrm{m}}/0.3{)}^{0.5}$, obtaining $S_8=0.794\pm 0.017$ ($\mathrm{\Lambda }\mathrm{CDM}$) and $S_8=0.817\pm 0.021$ ($w\mathrm{CDM}$), and a $\sim 10\%$ constraint on ${\mathrm{\Omega }}_{\mathrm{m}}$, obtaining ${\mathrm{\Omega }}_{\mathrm{m}}=0.259\pm 0.025$ ($\mathrm{\Lambda }\mathrm{CDM}$) and ${\mathrm{\Omega }}_{\mathrm{m}}=0.273\pm 0.029$ ($w\mathrm{CDM}$). In the context of the $w\mathrm{CDM}$ scenario, these statistics also strengthen the constraints on the parameter $w$, obtaining $w<-0.72$. The constraints from different statistics are shown to be internally consistent (with a $p$-value>0.1 for all combinations of statistics examined). We compare our results to other weak lensing results from the first three years of the Dark Energy Survey data, finding good consistency; we also compare with results from external datasets, such as planck constraints from the cosmic microwave background, finding statistical agreement, with discrepancies no greater than $<2.2\sigma$.

The dark dimension scenario, predicting one extra mesoscopic dimension in the micron range, has emerged by applying various swampland principles to the dark energy. In this note we find that realizing the grand unification of gauge forces is highly constraining in this context. Without actually constructing any grand unified theory (GUT) models, we argue that the mere assumption of grand unification of forces in this scenario, together with the experimental bounds on massive replicas of the Standard Model gauge bosons, predicts an upper bound for the GUT scale, $M_{\mathrm{GUT}}\lesssim {10}^{16}\mathrm{GeV}$. Combined with the experimental bound on the proton lifetime, this predicts that the $X$ gauge boson mediating proton decay is a 5D solitonic string of Planckian tension stretched across a length scale $L\sim (1–10\mathrm{TeV}{)}^{-1}$ ending on gauge branes of the same diameter $\sim L$. This leads to a mass of $M_X\sim {10}^{15}–{10}^{16}\mathrm{GeV}$. In particular assuming grand unification in the dark dimension scenario results in a tower of Kaluza-Klein excitations of Standard Model gauge bosons on the gauge branes in the 1–10 TeV range. This suggests that the diameter/separation $L$ of the gauge branes correlates with both the weak scale $\sim 1/L$ near a TeV and the GUT scale $\sim M_5^{2}L$ at ${10}^{16}\mathrm{GeV}$.

We show that the Kontsevich-Segal-Witten (KSW) criterion applied to the no-boundary state constrains anisotropic deformations of de Sitter space. We consider squashed $S^3$ and $S^1\times S^2$ boundaries and find that, in both models, the KSW criterion excludes a significant range of homogeneous but anisotropic configurations. For squashed $S^3$ boundaries, the excluded range includes all surface geometries with negative scalar curvature, in line with dS/CFT reasoning. For $S^1\times S^2$ boundaries, we find that KSW selects the low-temperature regime of configuration space where the $S^1$ is sufficiently large compared to the $S^2$. In both models, the KSW criterion renders the semiclassical wave function normalizable, up to one-loop effects.

TeV halos are extended very-high-energy (VHE; 0.1–100 TeV) gamma-ray emission around middle-aged pulsars. So far they have only been found around isolated pulsars, but it has been suggested that they may also be powered by millisecond pulsars (MSPs). We searched for VHE gamma-ray emission from MSPs reported by radio and GeV gamma-ray observatories in 2565 days of data from the High Altitude Water Cherenkov (HAWC) Observatory. We found no significant emission from individual pulsars. By combining the likelihood profiles of all MSPs accessible to HAWC, our analysis suggests that the excess emission around the MSP population is consistent with a background. Our result suggests that MSPs are not as efficient as isolated pulsars in producing TeV halos. This finding has strong implications on the physics interpretation of the Galactic Center GeV excess and high-latitude Galactic diffuse emission.