We investigate the dynamically generated $h_1$ state with spin-parity $J^P=1^{+}$ and a mass around 1790 MeV, arising from the $K^{*}{\overline{K}}^{*}$ interaction within the chiral unitary approach. The partial decay widths into the $K_1(1270)\overline{K}$ and $b_1(1235)\pi$ channels are calculated via a triangular-loop mechanism. In this mechanism, the $h_1$ state couples to $K^{*}{\overline{K}}^{*}$, and final-state interactions between $K^{*}$ and ${\overline{K}}^{*}$ proceed through pseudoscalar-meson exchange, leading to the final states $\overline{K}$ (or $\pi$) and $K_1(1270)$ [or $b_1(1235)$]. We also present the invariant-mass distributions of a vector meson and a pseudoscalar meson originating from the decays of $K_1(1270)$ or $b_1(1235)$, along with the corresponding decay widths. Our results show that these decay widths are all of the order of a few MeV. We hope that future experiments can test the predictions presented here, thereby helping to identify this $h_1$ state.

We summarize the formalism for calculating the exclusive dijet production in $ep\to e^{\prime }jjp$ in collinear QCD factorization, using generalized parton distributions as the soft hadronic input modeled in the double distribution approach. We include all leading-order contributions coming from light sea and valence quark exchanges, and gluon exchanges for both light quark-antiquark ($q\overline{q}$) production and also the heavy $c\overline{c}$ final state. We present results for several differential distributions for the cross section evaluated over a broad region of phase space, covering a wide range of inelasticity and photon virtuality. The gluon and sea contributions exhibit similar shapes, whereas the valence contribution, though relatively small, shows a markedly different behavior. The latter becomes particularly noticeable at large $x_{\mathbb{P}}$, a kinematic region not explored at HERA, but potentially accessible in future measurements at the Electron Ion Collider. This requires further feasibility studies. We also present the azimuthal angle modulation between the leptonic and the outgoing dijet planes for the general case, as well as for the ZEUS kinematic region where we see reasonable agreement with the data for diffractive deep inelastic scattering parameter $\beta \gtrsim 0.4$.

We study parity-violating birefringence induced by an asymmetric neutrino background in plasmas associated with active galactic nuclei (AGN). We derive a directionality factor arising from the relative bulk motion between the neutrino medium and plasma, and show that it can produce an anomalous frequency dependence of the polarization-rotation angle, distinct from the ${\omega }^{-2}$ scaling of Faraday rotation. This anomalous scaling can occur either at the resonance plasma frequency condition $\omega \simeq {\omega }_p$, or when $E_{\nu }^0\simeq m_{\nu }\omega /{\omega }_p$ lies within the range of the neutrino energy spectrum. We estimate the effect for three scenarios: jets propagating through the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$), jets with an internal flux of high-energy neutrinos, and accretion-disk plasma permeated by the $\mathrm{C}\nu \mathrm{B}$. Of the three scenarios, the latter gives the largest rotation angle ${\varphi }_{\mathrm{d}}\sim {10}^{-35}\mathrm{rad}$, at x-ray frequencies. Although the predicted rotation angles are below current polarimetric sensitivity, the identified spectral signatures provide a theoretical framework for probing neutrino asymmetries and AGN plasma properties independent of magnetic field models.

We perform detailed calculations of electroweak radiative corrections to parity violating lepton scattering with a proton target ($ep$ and $\mu p$) up to quadratic and reducible two-loop level using a covariant approach. Our numerical results are presented at energies relevant for a variety of existing and proposed experimental programs such as $Q_{\mathrm{weak}}$, P2, Measurement of a Lepton-Lepton Electroweak Reaction (MOLLER), Muon Scattering Experiment, and experiments at the Electron-Ion Collider. Analysis shows that such corrections at the next-to-next-to-leading order are quite significant and have to be included in searches of physics beyond the standard model, matching the increasing precision of the future experimental programs at low-energy scales.

The observable Universe has undergone periods of expansion that are well approximated by de Sitter (dS) space. Still lacking is a quantum-mechanical description of dS spacetime, both globally and when restricted to the static patch. We develop a novel prescription, to the best of our knowledge, for computing holographic complexity in the dS static patch to determine its microscopic features. Specifically, we propose that the natural candidate for dS complexity is the volume of extremal “timelike” surfaces restricted to the static patch, anchored to the cosmological horizon or an observer worldline. Our anchoring prescription provides a clear definition of a reference state, overcoming a common ambiguity in prior definitions of de Sitter holographic complexity. The late-time growth of our complexity functional is linear and proportional to the number of degrees of freedom associated with the cosmological horizon and, therefore, does not exhibit hyperfast growth. Our results imply the dS static patch is characterized by a quantum-mechanical system, with a finite-dimensional Hilbert space whose evolution is governed by a chaotic Hamiltonian.

We perform all possible supersymmetric truncations of the four-dimensional $\mathcal{N}=3$ dilaton Weyl multiplet, which realizes an $R$-symmetry $SU(2)\times U(1)\times U(1)$, to $\mathcal{N}=2$. A particular truncation procedure does not break any of the $R$-symmetries and leads to the known $\mathcal{N}=2$ vector-dilaton Weyl multiplet and the $\mathcal{N}=2$ vector multiplet. A different truncation procedure breaks the $SU(2)$ part of the $R$-symmetry to $U(1)$ and leads to a $32+32$ off-shell representation of $\mathcal{N}=2$ conformal supergravity with a partially broken $R$-symmetry. Independently, we construct another $32+32$ off-shell multiplet in $\mathcal{N}=2$ conformal supergravity by coupling the $\mathcal{N}=2$ scalar-tensor multiplet to the $\mathcal{N}=2$ standard Weyl multiplet and using the scalar fields present in the scalar-tensor multiplet to break the $SU(2)$ $R$-symmetry to $U(1)$. We then establish the equivalence between these two multiplets through a mapping. We observe that this $32+32$ multiplet is gauge equivalent to a Poincaré supergravity multiplet as it has all the compensators necessary to go from conformal supergravity to Poincaré supergravity.

We consider actions that are general functions of the world sheet/world volume metric and the induced metric for extended objects embedded in spacetime as Riemannian manifolds, area-metric manifolds, and volume-metric manifolds. For strings on a Riemannian spacetime, we consider general actions respecting volume-preserving diffeomorphisms (VPD), general diffeomorphisms, and diffeomorphisms with Weyl symmetry, respectivelyn. Well-known Schild, Nambu-Goto, and Polyakov actions are included as special cases. We reach two main conclusions: (1) When actions are functions of both the worldsheet metric and induced metrics, all nontrivial self-consistent actions are classically equivalent. (2) As a physical constraint on the classical action, VPD symmetry is as strong as the full diffeomorphism symmetry. The discussion is then extended to strings in spacetime manifolds equipped with the area or volume metrics. Then, we further consider higher-dimensional extended objects in spacetime defined with area or volume metrics, and show the equivalence between the generalized Schild actions and the generalized Nambu-Goto action. We prove a general theorem on VPD that explains this equivalence. Incidentally, while only the area metric is needed to define the string world sheet action, we show that the Polyakov action with an area-metric perturbation cannot describe critical strings without other interaction terms.

We study pairs of $4d$ $\mathcal{N}=1$ supersymmetric gauge theories that share the same vacuum moduli space and the same chiral field content, encoded by a common quiver, but differ in their superpotentials. These theories arise as worldvolume theories on a D3-brane probing a toric Calabi-Yau threefold and admit a description in terms of bipartite graphs on a 2-torus, known as brane tilings. Using an explicit example, we show that the correspondence is realized by a single “tilting” mutation along the diagonals of hexagonal faces in the brane tiling, which is equivalent to a specific sequence of Seiberg dualities performed at distinct gauge nodes in the quiver.

Type-IIB string theory on ${\text{AdS}}_3\times S^3\times T^4$ with Ramond–Ramond flux as the near-horizon limit of the D1-D5 solution is expected to be dual to a (4, 4) supersymmetric 2D conformal field theory (CFT) parametrized by the integers $Q_1$, $Q_5$, and other moduli. It is related by T-duality to type-IIA string theory in the near-horizon limit of the D2-D4 solution, which admits an uplift to the 11D ${\text{AdS}}_3\times S^3\times T^5$ background which is the near-horizon limit of the M2-M5 solution. We point out that this relation allows one to use the quantum M2-brane description to probe “nonplanar” corrections in the dual 2D CFT, in close analogy with the Aharony-Bergman-Jafferis-Maldacena (ABJM) theory case (described by M-theory on ${\text{AdS}}_4\times S^7/{\mathbb{Z}}_k$). We consider an analog of a supersymmetric Wilson loop (line defect) expectation value represented by a type-IIA string partition function expanded around an ${\text{AdS}}_2\subset {\text{AdS}}_3$ minimal surface. Its M-theory analog is the M2-brane partition function expanded near ${\text{AdS}}_2\times S^1$. We compute the one-loop contribution $Z_1$ to the M2-brane partition function and find that in contrast to the ABJM case in arXiv:2303.15207 [where $Z_1=(2\sin \frac{2\pi }{k}{)}^{-1}=\frac{k}{4\pi }+\frac{\pi }{6k}+\cdots$ contains an infinite series of higher-genera string corrections, $k^{-1}\sim \frac{g_s}{\sqrt{\mathrm{T}}}$], here it is given solely by the leading string theory contribution $Z_1=\frac{\kappa }{\sqrt{2\pi }}$, where $\kappa \sim \sqrt{Q_5}$ plays a role analogous to $k$. We also discuss a generalization to the mixed-flux case which is straightforward from the 11D perspective.

The Bern-Carrasco-Johansson (BCJ) double-copy construction reveals a fundamental structural connection between gauge and gravity theories. At its core, the BCJ double copy is directly due to a duality between the algebraic relations of a color root and those of a kinematic root. We generalize this principle beyond the conventional Lie algebra structure of tree-level Yang-Mills theory. By demanding color-kinematics duality for the complete basis of four-point color structures—including those involving the symmetric $d^{abc}$ constants—we define the universal double copy. We systematically classify the bases of all such parity-even generalized gauge-theory numerators and, independently, the space of all parity-even four-graviton higher-derivative operators. We demonstrate that our universal double-copy construction precisely spans the entire tower of parity-even four-graviton amplitudes in any dimension, except for the Lovelock $R^3$ contribution in $D>6$ which we can express in terms of a particularly simple universal triple-copy involving gauge theories coupled to scalars. Explicit machine-readable expressions for the complete basis of gauge-theory numerators and fundamental gravitational building blocks are provided in the Supplemental Material. This establishes that all possible four-point gravitational interactions can be factorized into products of gauge-theory building blocks governed by this universal notion of color-kinematics duality.

Material science and engineering have benefited from the use of geometric and topological tools. A material medium can mimic effective gravitational fields while spacetime metrics serve as geometric models of physical media. Although analog models of optical, acoustic, and viscous media in curved spacetimes are well established, none have yet captured the hallmark constitutive properties of superconductors. In this work we show that the Gödel universe—an exact solution to Einstein’s field equations—serves as the gravitational analog of a superconducting medium in its Meissner state.

The Barbero-Immirzi parameter $\gamma$ appears as a coupling constant in the spinfoam dynamics of loop quantum gravity. In this work, we highlight that $\gamma$ can be understood as a measure of gravitational parity violation via a duality rotation for the Engle-Pereira-Rovelli-Livine spinfoam model. We call this property $\gamma$-duality, and we investigate an effective field theory for gravity and a scalar field with the same degree of parity violation. The resulting relation between the coupling constants of parity-even and parity-odd higher-curvature terms in the effective action is determined by $\gamma$, opening the possibility of its measurement in the semiclassical regime. For a choice of $\gamma$-dual effective action, we study cosmic inflation and show that the observation of a primordial tensor polarization, together with the tensor tilt and the tensor-to-scalar ratio, provides a measurement of the Barbero-Immirzi parameter and, therefore, of the scale of discreteness of the quantum geometry of space.

This paper presents solutions to Einstein’s equation, and the numerical methods used to construct them, that describe simple cosmological models on manifolds with compact nonorientable spatial slices. These solutions have been constructed on a selection of manifolds having positive, negative, and vanishing spatial scalar curvatures. One example is shown to be indistinguishable locally from a homogeneous Friedman cosmological model, and others are constructed with significant inhomogeneities. Together, these examples are used to explore the strengths and limitations of the numerical methods used in this study, and to test the code used to implement them.

We investigate the impact of a late-time transition in the standardized absolute magnitude $M$ on the best-fit values of cosmological parameters using the $\mathrm{Pantheon}+\mathrm{dataset}$. Extending previous analyses which focused on flat $\mathrm{\Lambda }\mathrm{CDM}$, we examine this transition within flat $\mathrm{\Lambda }\mathrm{CDM}$ (Lambda Cold Dark Matter), wCDM (cold dark matter with a constant dark energy equation of state w), and CPL (Chevallier-Polarski-Linder) cosmologies as well as a model-independent cosmographic expansion, employing both frequentist (${\chi }^2$ minimization with Akaike Information Criterion/Bayesian Information Criterion) and Bayesian (Markov-chain Monte Carlo and nested sampling) inference frameworks. We confirm that the data consistently favor a step in absolute magnitude of $\mathrm{\Delta }M\simeq 0.19\mathrm{mag}$ at a characteristic distance of $d_{\mathrm{crit}}\approx 20\mathrm{Mpc}$. The inclusion of this transition leads to a statistically significant improvement in the quality of fit and has a distinct impact on parameter estimation: it induces a systematic increase in the inferred Hubble constant of approximately 2% across all tested models. In contrast, we find that the dynamical parameters governing the background expansion, including the matter density ${\mathrm{\Omega }}_m$ and the dark energy equation of state ($w_0,w_a$), remain stable and largely unaffected. These results indicate that the 20 Mpc feature acts primarily as a low-redshift calibration shift rather than a modification of the late-time expansion history.

Over the next decade, $\mathcal{O}(100)$ diffuse supernova neutrino background events are expected to be detected in the upcoming Hyper-Kamiokande experiment. Another neutrino source that has received far less attention in the context of neutrino detection is binary neutron star mergers. Including the data from multiple recent simulations, we find that detection in current and near-future neutrino experiments is not feasible, and a megaton-scale detector with $\mathcal{O}(10)\mathrm{MeV}$ threshold, such as the proposed Deep-TITAND, MEMPHYS, or MICA, will be required. This is primarily due to the updated binary neutron star merger rate and the time-of-flight delay caused by the nonzero neutrino mass. Regarding the former, recent results from the fourth observing run by LIGO, Virgo, and KAGRA has significantly lowered the upper limit on the neutron star merger rate. As for the latter, neutrino events from neutron star mergers are expected to be recorded shortly after the gravitational wave signal associated with the coalescence. Limiting the analysis to such short time windows can significantly reduce background rates. While this approach has been qualitatively discussed in the literature, the effect of the time delay caused by nonzero neutrino mass, which can substantially extend the observation windows, has been disregarded. We present a refined analysis employing energy-dependent time windows and luminosity distance cuts for the mergers and provide realistic estimates of the detector runtime required to record neutrinos from binary neutron star mergers with small background contamination. The relative timing between the neutrino and gravitational wave signals can also be employed to probe the scale of neutrino mass. We find that the sensitivity to the lightest neutrino mass exceeds both the most stringent terrestrial bounds from KATRIN and the projections based on galactic supernovae. This level of sensitivity may become particularly relevant in the future if terrestrial and supernova constraints are not significantly improved.

Very high energy (VHE) gamma rays in pulsars, and their surrounding halos, are interpreted to originate from the leptonic channel and electromagnetic interactions through electron inverse Compton scattering. In the hadronic scenario, TeV-PeV gamma rays are generated from the decay of neutral pions, which are produced from cosmic ray (CR) protons interacting with the ambient medium. Recent observations of sub-PeV gamma rays from the halo of the pulsar PSR $\mathrm{J}0622+3749$ by the Large High Altitude Air Shower Observatory Kilometer-Square Array provide an opportunity to investigate the underlying emission mechanisms. Previous studies have shown that the observed emission can be consistently explained within a leptonic framework by the slow diffusion of electrons. In this work, we explore an alternative explanation based on the hadronic scenario through the proton-proton ($pp$) interaction channel, incorporating the observation of VHE gamma rays at 7 TeV by the high-altitude water Cherenkov detector. To model the observed gamma-ray spectrum, ranging from $\sim 7\mathrm{TeV}$ up to 200 TeV, the required CR proton luminosity is found to be ${\eta }_p\sim 0.14$ of the spin-down luminosity of PSR $\mathrm{J}0622+3749$. This scenario assumes that protons propagate in a one-zone superdiffusive environment, characterized by a diffusion index of $\alpha =1.05$, within an ambient density of $1{\mathrm{cm}}^{-3}$.

To shed light on the inner structure of the observed single-bottom strange baryons, in this work we systematically study the Okubo-Zweig-Iizuka allowed strong decay properties of $1P$- and $2S$-wave ${\mathrm{\Xi }}_b$ and ${\mathrm{\Xi }}_b^{\prime }$ baryons within the $j\text{−}j$ coupling scheme in the framework of the quark pair creation model. For a comparison, we also give the predictions of the chiral quark model. The calculations indicate that (i) The $1P$-wave $\lambda$-mode ${\mathrm{\Xi }}_b$ states ${\mathrm{\Xi }}_b|J^P=1/2^{-},1{⟩}_{\lambda }$ and ${\mathrm{\Xi }}_b|J^P=3/2^{-},1{⟩}_{\lambda }$ are highly promising candidates for the observed state ${\mathrm{\Xi }}_b(6087)$ and ${\mathrm{\Xi }}_b(6095)/{\mathrm{\Xi }}_b(6100)$, respectively. The $1P$-wave $\lambda$-mode ${\mathrm{\Xi }}_b^{\prime }$ states ${\mathrm{\Xi }}_b^{\prime }|J^P=3/2^{-},2{⟩}_{\lambda }$ and ${\mathrm{\Xi }}_b^{\prime }|J^P=5/2^{-},2{⟩}_{\lambda }$ are likely candidates for the state ${\mathrm{\Xi }}_b(6227)$. Meanwhile, we cannot rule out the possibility that ${\mathrm{\Xi }}_b(6227)$ could be a candidate of the $1P$-wave $\rho$-mode ${\mathrm{\Xi }}_b$ state ${\mathrm{\Xi }}_b|J^P=3/2^{-},2{⟩}_{\rho }$ or ${\mathrm{\Xi }}_b|J^P=5/2^{-},2{⟩}_{\rho }$. (ii) For the other $1P$-wave $\rho$-mode ${\mathrm{\Xi }}_b$ states and $1P$-wave $\lambda$-mode ${\mathrm{\Xi }}_b^{\prime }$ states, they may be moderate states with a width of several tens of MeV. Their main decay channels are ${\mathrm{\Xi }}_b\pi$, ${\mathrm{\Xi }}_b^{\prime }\pi$, ${\mathrm{\Xi }}_b^{*}\pi$ or ${\mathrm{\Lambda }}_b\overline{K}$. The width of the $1P$-wave $\rho$-mode ${\mathrm{\Xi }}_b^{\prime }$ states are slightly broader, approximately several tens to over one hundred MeV, and the dominant decay channels are ${\mathrm{\Xi }}_b^{\prime }\pi$, ${\mathrm{\Xi }}_b^{*}\pi$, ${\mathrm{\Sigma }}_{b}K$ or ${\mathrm{\Sigma }}_b^{*}K$. (iii) The $2S$-wave $\lambda$-mode ${\mathrm{\Xi }}_b$ and ${\mathrm{\Xi }}_b^{\prime }$ states are most likely to be relatively narrow state with a width of only a few to around ten MeV, and they mainly decay into ${\mathrm{\Xi }}_b^{\prime }\pi$ or ${\mathrm{\Xi }}_b^{*}\pi$. Meanwhile, the decay process of $2S$-wave $\lambda$-mode ${\mathrm{\Xi }}_b^{\prime }$ states into the final states containing $1P$-wave ${\mathrm{\Xi }}_b$ baryons should not be overlooked either. We hope that the theoretical results can provide some reference for future experimental investigations.

We perform a feasibility study to probe dark matter (DM) production at the LHC within a global $U(1{)}_L$ scotogenic model. The study is conducted using the Markov chain Monte Carlo numerical method, considering the viable parameter space of the model allowed by experimental constraints such as neutrino oscillation data, the Higgs to invisible branching fraction, and DM observables. The production of scalar and fermionic DM candidates, predicted by the model, is then studied under the LHC conditions for different luminosity scenarios imposing compressed mass spectra conditions between the lightest fermion and the ${\mathbb{Z}}_2$ odd scalars. We study two production mechanisms, Drell-Yan and vector boson fusion. We find that the Drell-Yan mechanism gives better detection prospects for fermionic DM masses between 100 and 220 GeV at high-luminosity scenarios.

We investigate the dimension-8 gluonic quartic gauge couplings at future high-energy muon colliders through the process ${\mu }^{+}{\mu }^{-}\to gg\gamma$. Using detailed event simulation and optimized kinematic selections, we derive projected sensitivities to the Wilson coefficients and their associated new-physics scales, showing that muon colliders can probe deep into the multi-TeV regime and significantly surpass current LHC bounds. We further present the positivity bounds on those Wilson coefficients, as theoretical constraints from the fundamental principles of quantum field theory. Our results establish ${\mu }^{+}{\mu }^{-}\to gg\gamma$ as one of the most sensitive probes of dimension-8 new physics at future muon colliders.

We explore the idea of quark-lepton unification at low energies. In particular, we discuss the minimal framework for matter unification at the multi-TeV scale, in which neutrino masses are necessarily generated via the inverse seesaw mechanism. To assess the testability of this theory for physics beyond the Standard Model, we analyze current experimental constraints and derive the corresponding lower bound on the symmetry breaking scale. We reexamine the impact of existing limits from lepton number violating meson decays, taking into account the freedom associated with unknown quark-lepton mixing angles. Furthermore, we study the correlation between bounds from meson decays and $\mu \to e$ conversion. We demonstrate that the upcoming $\mu \to e$ conversion experiment at Fermilab can play a crucial role in probing quark-lepton unification at the multi-TeV scale.