Under the hypothesis that the $f_0(1370)$ is a $\kappa \overline{\kappa }$ molecular state, we calculate the partial widths of its various decay channels, including the two-body decays $K\overline{K}$, $\pi \pi$, and $\eta \eta$ and the four-body decays $\rho \rho /\sigma \sigma \to 4\pi$ and $K\overline{K}\pi \pi$. Treating the coupling $g_{f_0(1370)\kappa \overline{\kappa }}$ as a free parameter, we find that a value of 25–40 GeV brings the total width of $f_0(1370)$ in line with the measured value 200–500 MeV. At the center-of-mass energy $\sqrt{s}=1.37\mathrm{GeV}$, the channels that mainly contribute to the total width are $K\overline{K}$, $\pi \pi$, and $4\pi$ ranked as $\mathrm{\Gamma }(K\overline{K})>\mathrm{\Gamma }(4\pi )>\mathrm{\Gamma }(\pi \pi )$ with $g_{f_0(1370)\kappa \overline{\kappa }}=35\mathrm{GeV}$. Around 1.37 GeV, the decay widths of the two-body channels $K\overline{K}$, $\pi \pi$, and $\eta \eta$ remain stable with variation in $\sqrt{s}$, whereas the decay widths of the four-body channels $4\pi$ and $K\overline{K}\pi \pi$ increase continuously with $\sqrt{s}$. Most current data are model dependent and conflicting, particularly regarding the conclusion of $4\pi$ dominance and the ratio of $K\overline{K}$ to $\pi \pi$ decay widths. The current data cannot rule out the $\kappa \overline{\kappa }$ assignment for $f_0(1370)$. Further reliable theoretical and experimental analyses of $f_0(1370)$ are required to reveal its nature.

We compute the cross sections for the two-photon processes $\gamma \gamma \to {\pi }^0{\pi }^0$ and $\gamma \gamma \to K_S^0{K}_S^0$ in $k_T$ factorization, including the chirally enhanced two-parton twist-3 light cone distribution amplitudes. For these charge-suppressed neutral channels the twist-3 cross sections exceed the twist-2 ones by close to an order of magnitude in the intermediate-energy region, bringing the predictions much closer to the Belle data, the residual underestimate being plausibly attributable to higher-order QCD corrections. The calculation reproduces the measured angular distributions and the energy dependence of the charged channels and the neutral pion, though not the steeper fall of the neutral kaon. The neutral-to-charged ratios are the most discriminating observables. They depend strongly on energy in the data, whereas our calculation, like other approaches in the literature, yields a nearly flat ratio. Finally, in a phenomenological discussion, we combine our contribution with the soft handbag contribution and largely reproduce the observed energy dependence, suggesting that the hard and soft contributions are comparably important in the few-GeV region.

The nature of dark matter (DM) remains one of the most challenges in modern physics. Composite or macroscopic DM present a compelling alternative to conventional particle DM, yet their terrestrial search is notoriously challenging due to low number density. This article presents a unified, multimessenger search strategy for composite DM, dramatically improving existing constraints and proposing a new detection method. We first perform a model-independent update of astrophysical constraints from compact objects, utilizing systematic calculations and additional white dwarf data related to ignition and subsequent supernovae. Crucially, for the first time, we explore novel signals of composite DM in future gravitational wave detectors like LISA, TianQin, and Taiji, performing detailed signal-to-noise ratio and Fisher matrix analyses. We demonstrate that these detectors will possess the requisite sensitivity to probe untouched regions of the DM parameter space. Our results underscore the unique power of the multimessenger paradigm—spanning stellar astrophysics and gravitational wave astronomy—to explore this distinct and challenging frontier of DM physics. Our analyses extend broadly to a wide range of macroscopic or composite DM scenarios.

We revisit the $CP$-odd form factor in the $HWW$ vertex within the Standard Model, which is induced only at the one-loop level when one of the $W$ bosons is off-shell. To the best of our knowledge, the numerical evaluation of this form factor is presented for the first time. The relevant contributions from quark loops are of order ${10}^{-5}$, well below the current experimental sensitivity. The phenomenological implications are studied through asymmetries in unpolarized and polarized observables in three-body decays.

We present the first combined oscillation analysis of recent atmospheric neutrino datasets, featuring data from Super-Kamiokande, IceCube-DeepCore, and KM3NeT/ORCA together with reactor data from Daya Bay. Such combinations have long been considered infeasible outside experimental collaborations; we demonstrate that a unified physics model can simultaneously describe all datasets with no significant parameter tensions. Fitting 839 048 events across 1536 bins with 91 parameters, our combined analysis yields competitive measurements of the neutrino mixing parameters, and prefers the normal over the inverted mass ordering at $3\sigma$ significance.

We give an explicit description (in component fields) of a holomorphic theory associated to a general supersymmetric background of $\mathcal{N}=1$ supergravity in ten dimensions. Conjecturally, this provides a sought-for holomorphic realization of the supergravity twist in such backgrounds, generalizing the minimal type I BCOV theory for Calabi-Yau manifolds. Our theory unpacks the recently introduced Courant contact model associated to a holomorphic Courant algebroid. We also show that a coisotropic reduction of this model reproduces the recent model of Ashmore, Ibarra, Strickland-Constable, and Svanes [J. High Energy Phys. 03 (2026) 152]. which is formulated in terms of constrained fields.

We introduce a novel reformulation of three-dimensional gravity in terms of divergenceless vector frames, inspired by the double copy for Chern-Simons theory. This formulation is on-shell equivalent to conventional 3D gravity and provides a transparent geometric interpretation of the double copy construction. We relate the resulting theory to a Chern-Simons–like action, propose a higher-dimensional origin, and explore extensions that give rise to ${AdS}_3$ solutions.

We show that Maxwell theory with a codimension-1 Chern-Simons interface may support chiral electromagnetic surface waves on the interface, even when the bulk theory on both sides is conventional vacuum electrodynamics in infinite space. Solving the exact boundary value problem, we find that the Chern-Simons interaction acts with opposite sign on the two helicities oriented along the interface, giving rise to one normalizable mode localized on the interface. This mode is a gapless chiral surface photon with linear dispersion and a frequency-independent index of refraction set by the Chern-Simons coefficient. This mode exists despite the absence of bulk ambient material response or geometric confinement.

Conventional nuclear magnetic resonance searches for the galactic axion wind face technical challenges at lower frequencies, where the sensitivity of inductive readout scales less efficiently. In the pulsed architecture, a nuclear control sequence filters the axion field, a final $\pi /2$ pulse maps phase onto population, and the electron spin reads the resulting hyperfine-conditioned shift. We demonstrate analytically that this dispersive upconversion preserves the specific sidereal and annual modulation signatures required to distinguish dark matter signals from instrumental backgrounds. When instantiated in a silicon ${}^{209}\mathrm{Bi}$ donor platform, the hybrid sensor is projected to outperform direct nuclear detection by more than an order of magnitude over the mass range ${10}^{-16}–{10}^{-10}\mathrm{eV}$. With additional collective and resonant enhancements, the design can reach discovery-level sensitivity to Dine-Fischler-Srednicki-Zhitnitsky-scale axion-nucleon couplings after integration over the measurement time, establishing hyperfine-mediated sensing as a compact solid-state path for dark-matter searches.

Light crossing dark domain walls that source a top form coupled to gauge Chern-Simons terms mixing visible and dark $U(1)$ gauge fields generically convert into dark photons. The effect is entirely localized on the wall and requires no additional ingredients. The conversion rate is a sharp function of the photon frequency in the wall rest frame, vanishing above the ultraviolet cutoff of the top form sector. Partial cloaking may also induce a rotation of the polarization of transmitted light of order $\mathrm{\Delta }\vartheta \sim {10}^{-3}$ radians, modify the cosmic microwave background power spectrum, and violate Etherington’s reciprocity relation at low frequencies. These effects can impact cosmological determinations of the Hubble rate.

We investigate quantum information–theoretic observables in electron-proton scattering at the Electron-Ion Collider (EIC). Our analysis focuses on entanglement and magic, two complementary indicators of nonclassicality in quantum states. We show that while unpolarized and longitudinally polarized beams yield unentangled separable outcomes, transverse beam polarization enables the generation of entangled and nonstabilizer states. This result holds for both elastic and deep inelastic electron-proton scattering in QED. In the deep inelastic regime, the degree of quantum correlation is governed by the transversity parton distribution functions. Moreover, in the forward limit ($Q^2\to 0$), the standard model predicts vanishing entanglement, furnishing a clean null test: any nonzero signal would indicate new physics, especially from helicity-flipping or chiral interactions. These results establish the EIC as a promising environment for generating entangled and nonstabilizer states in high-energy physics, and they highlight opportunities for future lepton-hadron colliders to extend such studies into new kinematic domains.

We apply the dictionary of gauge-gravity dualities to study the spectrum of bound states in a special one-parameter family of strongly coupled, confining field theories in four dimensions. The top-down, holographic gravity dual description of this class of theories has been identified recently. It consists of nonsupersymmetric regular background solutions of Romans half-maximal supergravity theory in six dimensions, in the presence of a nontrivial Abelian magnetic flux along a compactified direction of the geometry. A zero-temperature, deconfinement, first-order phase transition appears at one end of this branch of solutions. It is triggered by the strength of the flux, setting an upper bound on the magnitude of the magnetic flux that can be supported by the geometry. We compute the spectrum of fluctuations of the background fields in the gravity description that corresponds to field-theory bound states. Two scalar particles are the lightest in the spectrum, their masses being suppressed and almost degenerate across the whole parameter space. Away from the transition, the heaviest between these two particles is identified as a dilaton, the pseudo-Nambu-Goldstone boson associated with scale invariance. It couples to the trace of the stress-energy tensor of the dual field theory, while the lightest scalar does not. In the range of parameter space closest to the extremum of the one-parameter family, near the first-order phase transition, a region with large curvature appears at the end of space of the geometry of the solutions. In this range, the two scalars mix nontrivially, and their masses are parametrically suppressed, with respect to the other bound states.

The spin foam approach to quantum gravity aims at providing a covariant path-integral formulation of canonical loop quantum gravity. Since spin foam amplitudes are defined through discretizations of spacetime, understanding the continuum limit of the theory remains a central open problem. In this work, we investigate the structural aspects of this limit in a model-independent manner. We introduce an axiomatic framework for spin foam amplitudes inspired by Atiyah’s formulation of topological quantum field theories (TQFTs). In this setting, Hilbert spaces and amplitudes are assigned to combinatorial and topological data associated with triangulated manifolds. By equipping the set of triangulations with suitable orders, this framework provides a precise notion of continuum limit and allows us to analyse its properties independently of any specific model. We systematically investigate how the specifics of the limit procedure allow to go beyond TQFT in the continuum. Under natural assumptions on the convergence of spin foam amplitudes, we establish a no-go result: sufficiently strong notions of convergence necessarily lead to a topological theory. Motivated by this obstruction, we weaken the notion of convergence and consider the continuum limit of spin foam amplitudes in a distributional sense, in the spirit of refined algebraic quantization. Under this assumption, the amplitude associated with the cylinder defines a rigging map, yielding a canonical construction of the physical Hilbert space. The resulting continuum amplitudes act as well-defined distributions on this space of physical states, characterizing this formulation of the gravitational path integral as physical in a precise sense.

We consider the algebra of observables of perturbative quantum gravity in the exterior of a stationary black hole or the static patch of de Sitter spacetime. It was previously argued in Refs. [1–3] that the backreaction of gravitons on the spacetime perturbs the area of the horizon at second order, which gives rise to a nontrivial constraint on the algebra of physical observables in the subregion. The corresponding “dressed” algebra including fluctuations of the total horizon area admits a well-defined trace and is type II. In this paper we show that, at the same perturbative order at which the horizon area (and angular momentum) fluctuates, gravitational backreaction also perturbs the horizon area in an angle-dependent way. These fluctuations are encoded in horizon charges—i.e., “edge modes”—which are related to an infinite dimensional “boost supertranslation” symmetry of the horizon. Together, these charges impose an infinite family of nontrivial constraints on the gravitational algebra. We construct the full algebra of observables which satisfies these constraints. We argue that the resulting algebra is type II and its trace is shown to take a universal form. The entropy of any “semiclassical state” is the generalized entropy with an additional edge mode contribution as well as a state-independent constant. For any black hole spacetime, the algebra has no maximum entropy state and is type ${\mathrm{II}}_{\infty }$. In de Sitter, the static patch is defined relative to the worldline of a localized “observer.” We show that a consistent quantization of the static-patch algebra requires a more realistic model of the observer, in which higher multipole moments perturb the “shape” of the cosmological horizon. We argue that a proper account of the observer’s rotational kinetic energy and (nongravitational) binding energy implies that the algebra is of type ${\mathrm{II}}_1$ and thereby admits a maximum entropy state.

Building on the earlier work by Araki and Tanii, Aschieri et al., and Buratti et al., we demonstrate that every model for self-dual nonlinear electrodynamics in four dimensions has a $\mathsf{U}(1)$ duality-invariant extension to $4p>4$ dimensions, and construct new self-dual nonlinear theories for a gauge ($2p-1$)-form. We present a family of models for self-dual nonlinear ($2p-1$)-form electrodynamics in which the trace of the energy-momentum tensor determines the flow with respect to a duality-invariant deformation parameter. Finally, we propose the interesting problem of computing the so-called induced action in the case that self-dual ($2p-1$)-form electrodynamics is coupled to dilaton and axion fields, and the compact duality group $\mathsf{U}(1)$ is enhanced to the noncompact group $\mathsf{SL}(2,\mathbb{R})$.

Rovibrational transitions in the hydrogen and antihydrogen molecular ions ${\mathrm{H}}_2^{+}$ and ${\overline{\mathrm{H}}}_2^{-}$ offer the possibility of testing Lorentz and $CPT$ symmetry to extremely high precision, in principle attaining $O({10}^{-17})$. In this paper, the third in a series, we give a comprehensive derivation of the rovibrational spectrum of ${\mathrm{H}}_2^{+}$ and ${\overline{\mathrm{H}}}_2^{-}$ in the standard model extension (SME), an effective quantum field theory incorporating Lorentz and $CPT$ violation. New developments described here include a complete analysis of the molecular dynamics from first principles in terms of the spherical tensor representation of the SME couplings, the systematic extension of our previous results to the nonminimal SME, a full description of the quantum number dependence of the rovibrational energy levels in the spherical tensor formalism with both high and low background magnetic fields, and an extended discussion of sidereal and annual variations of transition frequencies arising from both rotations and Lorentz boosts. The resulting sensitivity of the rovibrational spectrum to an extended range of SME couplings, together with the ability to isolate their individual effects using the quantum number dependence of the transition frequencies, enhances the opportunities to detect Lorentz and $CPT$ symmetry breaking through rovibrational spectroscopy of ${\mathrm{H}}_2^{+}$ and ${\overline{\mathrm{H}}}_2^{-}$.

We provide strong evidence for spontaneous breaking of spacetime parity persisting to arbitrarily high temperatures in a local, unitary, ultraviolet-complete quantum field theory in $2+1$ dimensions. The theory is defined by a renormalization group trajectory, triggered by a relevant deformation of a conformal field theory, consisting of a critical biconical vector model and a free massless Dirac fermion. This deformation couples the fermion to the scalar sector, generating a renormalization group flow that terminates at a nontrivial infrared fixed point described by a conformal Gross-Neveu-Yukawa model and a decoupled critical vector model. By construction, the quantum field theory is parity invariant at zero temperature. However, we show that at sufficiently high temperatures, parity symmetry is spontaneously broken and remains so even in the infinite-temperature limit. Our analysis relies on both, perturbative renormalization group techniques in $4-\epsilon$ dimensions and functional renormalization group techniques directly in $2+1$ dimensions.

We present a unified framework for the discussion of black hole thermodynamics of $d$-dimensional static black holes with spherical or compact hyperbolic horizon topology satisfying $g_{tt}{g}_{rr}=-1$ in Schwarzschild gauge. To that end, we consider any such black hole as a solution to an integrable two-dimensional effective dilaton theory and thereby as a vacuum solution to a generalized notion of $d$-dimensional quasitopological gravity. We show that the generating function determining $f(r)=-g_{tt}$ in the integrated equation of motion provides the thermodynamic mass in a generalized first law with entropy computed as the Wald entropy. The framework presented here can be applied to singular and regular black holes with flat or anti–de Sitter asymptotics.

Fermion-boson stars are compact equilibrium configurations composed of ordinary fermionic matter and a bosonic dark component interacting only through gravity. Such systems provide a natural framework for exploring deviations from standard neutron-star models, including the possible accumulation of dark matter inside neutron stars, and may be relevant for compact objects near the low-mass black hole gap. We construct static and uniformly rotating fermion-boson stars within the framework of $R$-squared $f(R)$ gravity, characterized by the functional form $f(R)=R+a{R}^2$, where $a$ is a positive parameter governing the effective mass scale from the scalar degree of freedom. The fermionic sector is modeled as a perfect fluid described by a tabulated equation of state at zero temperature, while the bosonic component is represented by a self-interacting complex bosonic field. Our results show that the scalar degree of freedom modifies the spatial distribution of both the bosonic field and the fermionic pressure, enlarges the domain of admissible equilibrium solutions, and increases the maximum supported masses relative to general relativity. Our models remain compatible with current astrophysical and gravitational-wave constraints, suggesting that fermion-boson stars in $R$-squared gravity offer a promising framework to investigate the combined effects of dark bosonic matter, rotation, and strong-field modifications of gravity in compact objects.

Black hole spacetimes contain several geometrically distinguished hypersurfaces, including event and Cauchy horizons, stationary-limit surfaces, and curvature singularities. These structures are usually identified by different geometric or causal criteria. We show that, for the Kerr-Newman black hole, the membrane-paradigm pressure of a stretched horizon admits an analytically continued scalar representative whose fully factorized form has zeros, poles, and singular factors aligned with these standard Kerr-Newman loci. Its zeros occur at the outer and inner horizons, its poles occur at the outer and inner stationary-limit surfaces, its higher-order divergence contains the ring-singularity factor, and its large-$r$ behavior records the asymptotic decay of the scalar. The construction is not proposed as a new invariant characterization of the spacetime, nor as a physical extension of the membrane fluid into the black hole interior. Rather, it gives a compact membrane-pressure-based diagnostic whose analytic structure reorganizes several familiar surfaces of the Kerr-Newman geometry. We also note a secondary, purely algebraic analogy with generalized multicomponent van der Waals-type equations of state.