Primordial gravitational waves could be non-Gaussian, just like primordial scalar perturbations. Although the tensor two-point function has thus-far remained elusive, the three-point function could, in principle, be large enough to be detected in cosmic microwave background temperature and polarization anisotropies. We perform a detailed analysis of tensor and mixed tensor-scalar non-Gaussianity through the Planck Public Release 4 bispectrum, placing constraints on 11 primordial templates, spanning various phenomenological and physical regimes including modifications to gravity, additional fields in inflation, and primordial magnetic fields. All analysis is performed using modern quasioptimal binned estimators and yields no evidence for tensor non-Gaussianity, with a maximum detection significance of $2\sigma$. Our constraints are derived primarily from large scales (except for tensor-scalar-scalar models) and benefit greatly from the inclusion of $B$-modes. Although we find some loss of information from binning, mask effects, and residual foreground contamination, our $f_{\mathrm{NL}}$ bounds improve over those of previous analyses by (20–700)%, with 6 of the 11 models being analyzed for the first time. Unlike for scalar non-Gaussianity, future low-noise experiments such as LiteBIRD, the Simons Observatory, and CMB-S4, will yield considerable improvement in tensor non-Gaussianity constraints.

In this paper, we propose an Alcock-Paczyński (AP) test to constrain cosmology using HII bubbles during the epoch of reionization. Similarly to cosmic voids, a stack of HII bubbles is spherically symmetric because ionizing fronts propagate isotropically on average (even if individual bubbles may not be spherical), making them standard spheres to be used in an AP test. Upcoming 21-cm observations, from the Square Kilometer Array (SKA), for instance, will contain tomographic information about HII regions during reionization. However, extracting the bubbles from this signal is made difficult because of instrumental noise and foreground systematics. Here, we use a neural network to reconstruct neutral-fraction boxes from the noisy 21-cm signal, from which we extract bubbles using a watershed algorithm. We then run the purely geometrical AP test on these stacks, showing that a SKA-like experiment will be able to constrain the product of the angular-diameter distance $D_{\mathrm{A}}$ and Hubble parameter $H$ at reionization redshifts with $\sim 2\%$ precision, robustly to astrophysical and cosmological uncertainties within the models tested here. This AP test, whether performed on 21-cm observations or other large surveys of ionized bubbles, will allow us to fill the knowledge gap about the expansion rate of our Universe at reionization redshifts.

Ultralight dark photon dark matter features distinctive cosmological and astrophysical signatures and is also supported by a burgeoning direct-detection program searching for its kinetic mixing with the ordinary photon over a wide mass range. Dark photons, however, cannot necessarily constitute the dark matter in all of this parameter space. In minimal models where the dark photon mass arises from a dark Higgs mechanism, early-Universe dynamics can easily breach the regime of validity of the low-energy effective theory for a massive vector field. In the process, the dark sector can collapse into a cosmic string network, precluding dark photons as viable dark matter. We establish the general conditions under which dark photon production avoids significant backreaction on the dark Higgs and identify regions of parameter space that naturally circumvent these constraints. After surveying implications for known dark photon production mechanisms, we propose novel models that set well-motivated experimental targets across much of the accessible parameter space. We also discuss complementary cosmological and astrophysical signatures that can probe the dark sector physics responsible for dark photon production.

The thermal Sunyaev-Zel’dovich effect (tSZ) is a sensitive probe of cosmology, as it traces the abundance of galaxy clusters and groups in the late-time Universe. Upcoming cosmic microwave background experiments such as the Simons Observatory (SO) and CMB-S4 will provide low-noise and high-resolution component-separated tSZ maps covering a large sky fraction. The tSZ signal is highly non-Gaussian; therefore, higher-order statistics are needed to optimally extract information from these maps. In this work, we study the cosmological constraining power of several tSZ statistics—Minkowski functionals (MFs), peaks, minima, and moments—that have yielded promising results in capturing non-Gaussian information from other cosmological data. Using a large suite of halo-model-based tSZ simulations with varying ${\mathrm{\Omega }}_c$ and ${\sigma }_8$ (154 cosmologies and over 800,000 maps, each $10.5\times 10.5{\mathrm{deg}}^2$), we show that by combining these observables, we can achieve $\approx 29\times$ tighter constraints compared to using the tSZ power spectrum alone in an idealized noiseless case, with the MFs dominating the constraints. We show that much of the MF constraining power arises from halos below the detection threshold of cluster surveys, suggesting promising synergies with cluster-count analyses. Finally, we demonstrate that these statistics have the potential to deliver tight constraints even in the presence of noise. For example, using post-component-separation tSZ noise expected for SO, we obtain $\approx 1.6\times$ and $\approx 1.8\times$ tighter constraints than the power spectrum with MFs and all statistics combined, respectively. We show that the constraints from MFs approach the noiseless case for white-noise levels $\lesssim 1\mu \mathrm{K}\text{−}\mathrm{arcmin}$.

The Compton amplitude subtraction function is an essential component in work concerning both the proton radius puzzle and the proton-neutron mass difference. However, owing to the difficulty in determining the subtraction function, it remains a key source of uncertainty in these two contexts. Here, we use the Feynman-Hellmann method to determine this subtraction function directly from lattice QCD. Furthermore, we demonstrate how to control dominant discretization artifacts for this calculation, eliminating a major source of systematic error. This calculation is performed for a range of hard momentum scales, and three different sets of gauge configurations for pion masses about 400 MeV. Our results show good agreement with continuum OPE expectations. As such, this work paves the way for model-independent and precise determinations of the subtraction function over a wide range of kinematics.

The brightest cosmic gamma-ray burst (GRB) ever detected, GRB 221009A, was accompanied by photons of very high energies. These gamma rays may be used to test both the astrophysical models of the burst and our understanding of long-distance propagation of energetic photons, including potential new-physics effects. Here we present the observation of a photonlike air shower with the estimated primary energy of ${300}_{-38}^{+43}\mathrm{TeV}$, coincident (with the chance probability of $\sim 9\times {10}^{-3}$) with the GRB in its arrival direction and time. Making use of the upgraded Carpet-3 muon detector and new machine learning analysis, we estimate the probability that the primary was hadronic as $\sim 3\times {10}^{-4}$. This is the highest-energy event possibly associated with any GRB.

We present complete results for the hadronic vacuum polarization (HVP) contribution to the muon anomalous magnetic moment $a_{\mu }$ in the short- and intermediate-distance window regions, which account for roughly 10% and 35% of the total HVP contribution to $a_{\mu }$, respectively. In particular, we perform lattice-QCD calculations for the isospin-symmetric connected and disconnected contributions, as well as corrections due to strong-isospin breaking. For the short-distance window observables, we investigate the so-called log-enhancement effects as well as the significant oscillations associated with staggered quarks in this region. For the dominant, isospin-symmetric light-quark-connected contribution, we obtain $a_{\mu }^{ll,\mathrm{SD}}(\mathrm{conn})=48.139(11{)}_{\mathrm{stat}}(91{)}_{\mathrm{syst}}[92{]}_{\text{total}}\times {10}^{-10}$ and $a_{\mu }^{ll,\mathrm{W}}(\mathrm{conn})=206.90(14{)}_{\mathrm{stat}}(61{)}_{\mathrm{syst}}[63{]}_{\text{total}}\times {10}^{-10}$. We use Bayesian model averaging to fully estimate the covariance matrix between the individual contributions. Our determinations of the complete window contributions are $a_{\mu }^{\mathrm{SD}}=69.05(1{)}_{\mathrm{stat}}(21{)}_{\mathrm{syst}}[21{]}_{\text{total}}\times {10}^{-10}$ and $a_{\mu }^{\mathrm{W}}=236.45(17{)}_{\mathrm{stat}}(83{)}_{\mathrm{syst}}[85{]}_{\text{total}}\times {10}^{-10}$. This work is part of our ongoing effort to compute all contributions to HVP with an overall uncertainty at the few-permille level.

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.