We propose a novel test of the unitarity of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix at collider experiments. Our approach exploits the incomplete cancellation between $t$-channel neutrino exchange and $s$-channel gauge-boson contributions that arises in the presence of violation of the flavor-diagonal PMNS unitarity conditions in weak boson pair production, leading to an anomalous growth of the cross section with energy. Such effects are generic in extensions of the Standard Model in which light neutrinos mix with heavier states, and can manifest at colliders as long as the characteristic energy of the process remains below the mass threshold of the new degrees of freedom. After briefly reviewing these scenarios, we employ our strategy to derive model-independent bounds on flavor diagonal unitarity-violating effects using LEP II data. We then present sensitivity projections for future lepton and hadron colliders, demonstrating that they are well suited to probe the unitarity of the neutrino mixing matrix with this method.

A nonsupersymmetric inverse seesaw model of neutrino mass based on the $A_5^{\prime }$ modular symmetry is presented. This framework provides a combined explanation for neutrino masses, mixing, and the cosmic baryon asymmetry through leptogenesis. Three concrete realizations are constructed, and their phenomenological predictions are analyzed. The results are not only compatible with the measured neutrino oscillation parameters within the current experimental $3\sigma$ ranges, but also provide predictions for the neutrino mass ordering, Dirac and Majorana $CP$-violating phases, and the effective Majorana mass in neutrinoless double beta decay. The model further realizes TeV-scale leptogenesis consistent with the observed baryon asymmetry, rendering the scenario testable in both low-energy neutrino experiments and high-energy collider searches.

We present nonperturbative results of the Casimir potential in non-Abelian SU(3) gauge theory in $(2+1)\mathrm{D}$ and $(3+1)\mathrm{D}$ in the confined and deconfined phase. For the first time, geometries beyond parallel plates in $(3+1)\mathrm{D}$ are explored and we show that the Casimir effect for the symmetrical tube and symmetrical box is attractive. The Casimir potential for the tube differs from the massless noninteracting scalar field theory prediction, where a repulsive Casimir potential is expected. Unlike the parallel plate geometry where the plate size is fixed, in the case of the tube and box, the sizes of the faces forming the walls of the geometries changes with separation distance. We propose various methods that can be used to account for the energy contributions from creating the boundaries. We show that increasing the temperature from a confined to a deconfined phase does not alter the Casimir potential. This observation is consistent with prior work suggesting that the region inside the walls is a boundary induced deconfined phase.

In this work, we explore a Bemfica-Disconzi-Noronha-Kovtun (BDNK)-type formulation of relativistic magnetohydrodynamics, providing a causal and stable first-order description of dissipative fluids. We derive coupled evolution equations for the temperature and magnetic field in a boost-invariant Bjorken background, restricting to ($0+1$)D dynamics while retaining all relevant first-order gradients. By varying the transport coefficients, we disentangle the interplay and mutual backreaction between the thermal and electromagnetic sectors. We find that, for comparable transport coefficients, the magnetic field is more sensitive to the temperature evolution than vice versa. We also examine the number density evolution, which is influenced by both temperature gradients and magnetic-field dynamics. We further investigate dilepton production, where the magnetic field modifies the emission rate through the relaxation time in a kinetic-theory framework. Relative to the baseline case with vanishing expansion coefficients, nonzero first-order coupling coefficients significantly modify the low-mass dilepton spectrum. For the positive coefficients considered here, the dilepton yield is enhanced by a factor of approximately 3–5, while negative coefficients lead to an overall suppression. Nevertheless, the central physical conclusion remains unchanged within the parameter range studied: coupling between temperature gradients and magnetic-field evolution accelerates the cooling of the medium, thereby reducing the dilepton yield compared to the case without this feedback. This qualitative behavior persists for both positive and negative expansion coefficients, although the overall yield depends on their values.

The parity-doublet model (PDM) is a chirally invariant effective theory for strong-interaction matter involving nucleons and their opposite-parity partners in a parity-doubling framework. We introduce a multiplicatively renormalizable mean-field approach to include the baryonic vacuum contributions to the resulting grand-canonical potential in an explicitly renormalization-group invariant form. As an application, we evaluate the pertinent thermodynamics of two-flavor symmetric and asymmetric nuclear matter, focusing on the restoration of spontaneously broken chiral symmetry at baryon densities and temperatures relevant for the astrophysics of neutron stars. Special attention is paid to the effect of the baryonic vacuum fluctuations on the evolution of the chiral condensate with baryon density and temperature for specific choices of the chirally invariant baryon mass $m_0$ to demonstrate the importance of consistently including these vacuum fluctuations in the PDM.

The charged current ${\nu }_{\mu }({\overline{\nu }}_{\mu })$-induced deep inelastic scattering (DIS) from an ${}^{40}\mathrm{Ar}$ target is studied using a microscopic framework that incorporates nuclear medium effects due to Fermi motion, binding energy, nucleon correlations, mesonic ($\pi$ and $\rho$) contributions, and nuclear shadowing and antishadowing across the relevant Bjorken-$x$ region. The nuclear structure functions $F_{iA}(x,Q^2)$ $(i=1-3)$ are evaluated using a relativistic nucleon spectral function ($S_h$) within the local density approximation employing the free nucleon structure functions, $F_{iN}(x,Q^2)$ $(i=1-3)$. These $F_{iN}(x,Q^2)$ $(i=1-3)$ are calculated using the parton distribution functions from the MMHT 2014 parametrization, including higher-order perturbative QCD corrections up to the next-to-next-to-leading order, along with the nonperturbative target mass corrections. The resulting nuclear structure functions $F_{iA}(x,Q^2)$ $(i=1-3)$ are subsequently used to compute the differential DIS cross sections for the ${}^{40}\mathrm{Ar}$ nucleus. Numerical results are presented for ${\nu }_{\mu }({\overline{\nu }}_{\mu })$ beam energies $E=4\mathrm{GeV}$ and $E=6\mathrm{GeV}$ for the differential scattering cross sections $\frac{d^2\sigma }{dxdy}$ and $\frac{d\sigma }{dx}$, relevant to the ongoing and upcoming liquid-argon neutrino experiments such as DUNE and the Fermilab short-baseline neutrino program.

We present global limits for Majorana neutrino masses by combining the latest results from neutrinoless double-beta ($0\nu \beta \beta$) decay searches and ab initio nuclear theory. Limits are derived in a Bayesian framework utilizing likelihood functions from a suite of $0\nu \beta \beta$-decay experiments in conjunction with nuclear matrix elements calculated from nuclear and electroweak forces derived from chiral effective field theory and implemented in the in-medium similarity renormalization group many-body approach. In contrast to nuclear models, ab initio results indicate that the current generation of $0\nu \beta \beta$-decay experiments have likely not yet reached sensitivities required to probe the mass regime allowed by neutrino-oscillation data, where the combined bounds are notably stronger than those given by individual experiments. Finally, from predicted sensitivities of next-generation searches, we show that, while no one individual experiment fully covers the inverted mass ordering, this can be achieved from combined contributions from the four key isotopes: ${}^{76}\mathrm{Ge}$, ${}^{100}\mathrm{Mo}$, ${}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$.

Recently, the ${\mathrm{JSNS}}^2$ Collaboration measured for the first time the missing-energy distribution of ${}^{12}\mathrm{C}$ using a monochromatic neutrino beam coming from kaon decays at rest. In this work, we present the results of an analysis of this spectrum using the relativistic distorted-wave approach. A new parametrization of the spectral function for neutrons in ${}^{12}\mathrm{C}$, which incorporates detailed information from $(e,e^{\prime }p)$ experiments with high missing-energy resolution, has been used. The role of the recoil of the residual nucleus, final-state interactions, and neutrino event generators are discussed.

The detection of a single quantum of energy with high efficiency and a low false positive rate is of considerable scientific interest, from serving as single quantum sensors of optical and infrared photons to enabling the direct detection of low-mass dark matter. We confirm our initial experimental demonstration of magnetic avalanches induced by scattering of quanta in single-molecule magnet (SMM) crystals made of ${\mathrm{Mn}}_{12}$ acetate, establishing the use of SMMs as particle detectors for the first time. Although the current setup has an energy threshold in the MeV regime, our results motivate the exploration of a wide variety of SMMs whose properties could allow for detection of sub-eV energy depositions.

We demonstrate that violent kinetic preheating following inflation can lead to the formation of black holes in the early Universe. In $\alpha$-attractor models with derivative inflaton couplings, nonlinear amplification of field fluctuations drives large spacetime curvature and gravitational collapse shortly after inflation ends. Using fully general-relativistic lattice simulations, we find that these dynamics produce black holes with masses of order tens of grams at subhorizon scales, without requiring large primordial curvature perturbations. Although such micro black holes evaporate rapidly via Hawking radiation, their formation modifies the postinflationary equation of state and their evaporation can successfully reheat the Universe before big bang nucleosynthesis. These results identify kinetic preheating as a new, efficient channel for black-hole production.

We consider a Universe with a three-torus topology, which before inflation is devoid of any matter or radiation. Its preinflationary evolution is driven solely by Casimir energies of the existing fields, with a radiationlike equation of state. We show that, under natural assumptions and with the appropriate number of fermions and bosons in the theory, such a Universe can start its evolution from a Planck size at the Planck time. Moreover, assuming typical parameters for inflation and reheating, the three-torus Universe can be several Hubble radii across at present time, which is precisely the size hinted by the anomaly in the cosmic microwave background observed at low multipole moments. We derive a relation between the size of the Universe, the number of $e$-folds of inflation, and the energy density decrease during reheating, which we then use to determine the parameter values consistent with the anomaly and the lower bound on the size of the Universe from the Planck satellite.

Gravitational-wave events are interpreted in terms of Bayesian posteriors for their source properties inferred under unphysical reference priors. Though these parameter estimates are important intermediate data products for downstream analyses, we demonstrate that they are generically biased and therefore should not be used for astrophysical interpretation directly, as is common. Hierarchical parameter estimation is the solution, as joint analysis of the entire catalog of observations reduces statistical uncertainties and actually informs the correct prior, with population-informed event parameters now appropriate for astrophysical interpretation. As an example, we show how the most extreme measurements from a catalog can be derived and used to identify exceptional events from previous and ongoing observing runs, pointing out they are more informative about the population than any individual event. Using LIGO-Virgo-KAGRA data, we thus demonstrate that population inference is not optional to interpret gravitational-wave observations.

Topological entanglement entropy (TEE) is an efficient way to detect topological order in the ground state of gapped Hamiltonians. The seminal work of Kitaev and Preskill [“Topological entanglement entropy,” Phys. Rev. Lett. 96, 110404 (2006)], and simultaneously by Levin and Wen [“Detecting topological order in a ground state wave function,” Phys. Rev. Lett. 96, 110405 (2006)] proposed separate definitions of TEE based on a subtraction scheme. In the present work, we explain why the subtraction schemes work for the computation of TEE and generalize them for an arbitrary number of subregions by explicitly noting the necessary conditions for an information quantity to capture TEE. Our analysis puts the two definitions [Kitaev and Preskill, “Topological entanglement entropy,” Phys. Rev. Lett. 96, 110404 (2006), Levin and Wen, “Detecting topological order in a ground state wave function,” Phys. Rev. Lett. 96, 110405 (2006)] into separate classes. Focusing on cyclic information quantities ${\mathcal{Q}}_{2n+1}$ and multi-information ${\mathcal{I}}_n$, we propose a generalized framework for defining TEE. We also show that the holographic entropy inequalities are satisfied by the quantum entanglement entropy of the nondegenerate ground state of a topologically ordered two-dimensional medium with a mass gap.

We consider a static open string in arbitrary stationary spacetime, which can represent a heavy quark-antiquark pair within the holographic framework or effective theory. Generally, the string profile is not symmetric with respect to the turning point, and the symmetry restores for a simple string configuration in backgrounds with certain constraints. We identify a wide family of metrics for which the symmetry is preserved, enabling a direct isolation of the linear-in-distance term in the static potential for simple symmetric string configurations, even in nondiagonal backgrounds. As a first example, we apply our formulas to the black brane dual to the $\mathcal{N}=4$ supersymmetric Yang-Mills (SYM) plasma at finite temperature. We find that the separation distance between quarks, $L$, is given in terms of a hypergeometric function, while the potential, $V$, consists of two distinct contributions: a term linear in the separation and a term that involves its derivative by temperature. Analysis of the leading terms in the series expansion reveals that the temperature corrections of the separation distance lead to the “swallowtail” behavior. Further, applying our formulas to the Rindler-anti–de Sitter (AdS) spacetime dual to an accelerated $\mathcal{N}=4$ SYM plasma, we obtain analytic expressions for the distance and potential in terms of the elliptic integrals, which in the large Hawking temperature (large acceleration or small curvature) limit come to the conformal results for pure AdS. Then, we show that the distance between quarks decreases, the static potential between them increases, and the characteristic temperatures increase with an acceleration, $a_c$. However, we observe that an acceleration-scaled potential, $a_{c}V$, as a function of the acceleration-scaled distance, $a_{c}L$, does not depend on the certain value of the acceleration.

We unveil a remarkable interplay between rigid field theories (RFTs), charge-to-mass ratios $\gamma$, and scalar curvature divergences ${\mathsf{R}}_{\mathrm{div}}$ in the vector multiplet moduli space of 4D $\mathcal{N}=2$ supergravities, obtained upon compactifying type II string theory on Calabi–Yau threefolds. We show that the condition to obtain an RFT that decouples from gravity implies a divergence in the $\gamma$ of (would-be) BPS particles charged under the rigid theory and vice-versa. For weak coupling limits, where the scalar curvature diverges, we argue that such BPS particles exist and that ${\mathsf{R}}_{\mathrm{div}}\lesssim {\gamma }^2$, implying that all these divergences are a consequence of RFT limits. More precisely, along geodesics we find that ${\mathsf{R}}_{\mathrm{div}}\sim ({\mathrm{\Lambda }}_{\mathrm{wgc}}/{\mathrm{\Lambda }}_g{)}^2$, where ${\mathrm{\Lambda }}_{\mathrm{wgc}}\equiv g_{\mathrm{rigid}}{M}_{\mathrm{Pl}}$ is the RFT cutoff estimate of the weak gravity conjecture and ${\mathrm{\Lambda }}_g=g_{\mathrm{rigid}}^{-2}{\mathrm{\Lambda }}_{\mathrm{RFT}}$ the electrostatic energy integrated up to its actual cutoff ${\mathrm{\Lambda }}_{\mathrm{RFT}}$.

We study the equation of motion of the Euclidean Ishibashi-Kawai-Kitazawa-Tsuchiya matrix model, and realize a new type of classical saddle that only exists in the $N\to \infty$ limit. Under the assumption that the matrices are the generators of $\mathfrak{so}(n,m)$, we identify a unique solution, that is, $\mathfrak{so}(1,3)$. Even though it has 6 generators and thus 6 nonzero matrices, they are not independent due to the 2 Casimir constraints in $\mathfrak{so}(1,3)$. Exploiting the Lie-algebraic structure and the Casimir constraints, we derive a four-dimensional space that a test scalar propagates on. The associated metric possesses SU(2) isometry, which is closely related to the Taub–Newman-Unti-Tamburino/Bolt geometry and may, more broadly, be related to black hole physics.

Plasma surrounding a black hole modifies light propagation and can alter the observed shadow, potentially affecting the interpretation of Event Horizon Telescope data. We study the effects of dark matter and nonmagnetized pressureless plasma on the shadow of a Kerr-like black hole by analyzing null geodesics in both homogeneous and inhomogeneous plasma distributions. For the homogeneous plasma profile, the asymptotic Bardeen coordinates acquire a refractive normalization factor arising from the leading-order coupling between the metric function $\mathrm{\Delta }(r)$ and the radial plasma function $f_r(r)\propto r^2$. We show that increasing the black hole spin generally enlarges the shadow radius and increases its deformation, while moving the observer away from the equatorial plane decreases both quantities. For the parameter ranges considered, astrophysically reasonable dark matter densities in this model do not produce appreciable changes in the photon trajectories. Plasma effects, however, are significant; increasing the plasma density increases the shadow radius and deformation for homogeneous plasma, but decreases them for inhomogeneous plasma. The energy emission rate likewise depends strongly on the plasma model, with homogeneous plasma producing a substantially larger rate as the plasma strength increases. As an illustrative benchmark, we compare the resulting geometric critical-curve sizes with EHT-inferred shadow-size intervals for M87* and Sgr A*.

Upgrades to current gravitational wave detectors for the next observation run and upcoming third-generation observatories, like the Einstein telescope, are expected to have enormous improvements in detection sensitivities and compact object merger event rates. Estimation of source parameters for a wider parameter space that these detectable signals will lie in will be a computational challenge. Thus, it is imperative to have methods to speed up the likelihood calculations with theoretical waveform predictions, which can ultimately make the parameter estimation faster and aid in rapid multimessenger follow-ups. In this work, we study autoencoder models for gravitational waveform generation by adopting the best-performing architecture of Liao and Lin [1] to approximate fixed duration 1 s long aligned-spin seobnrv4 inspiral-merger-ringdown waveforms. Our parameter space consists of four parameters, [$m_1$, $m_2$, ${\chi }_1(z)$, ${\chi }_2(z)$]. The masses are uniformly sampled in $[5,75]M_{\odot }$ with a mass ratio limit of $m_1/m_2<10$, while the spins are uniform in $[-0.99,0.99]$. Our model is able to generate ${10}^3$ waveforms in about ${10}^{-1}\mathrm{s}$ at an average speed of $50\mathrm{\mu s}$ per waveform on a graphics processing unit (GPU). This batched GPU generation is about 4 orders of magnitude faster than the serialized CPU generation by the base seobnrv4 implementation, and 2–3 orders of magnitude faster than existing non-machine-learning accelerated waveform variants. The median mismatch for the generated waveforms in the test dataset is $\sim {10}^{-2}$, with better accuracy in a restricted parameter space of ${\chi }_{\mathrm{eff}}\in [-0.80,0.80]$, however still less than that of other approaches. The latent sampling error of our model can be quantified at a median mismatch standard deviation of $4\times {10}^{-3}$. Although the accuracy of our model does not enable full production use yet, the model could be useful wherever a high volume of approximate theoretical waveforms are required, for instance, for rapid sky localization.

One of the main features of nonlinear electrodynamics is the existence of an effective geometry that describes the geodesic motion of photons. A detailed analysis of the properties of the effective geometry is of utmost importance for a better understanding of nonlinear electrodynamics theories and their possible imprints on physics, especially in the context of black holes. We consider a nonlinear electrodynamics model that depends on the two electromagnetic scalar invariants and obtain that the motion of photons in nonlinear electrodynamics exhibits vacuum birefringence, i.e., photons can propagate along two distinct paths, depending on their polarization. As a consequence of this phenomenon, we show that static black hole solutions sourced by nonlinear electrodynamics can admit two distinct unstable light rings, leading to the formation of two distinct shadows. Moreover, to explore the potential astrophysical relevance of our results, we compare them with the astrophysical observations for the shadow radius of Sagittarius A*. We place upper limits on the charge-to-mass ratio of the nonlinear electrodynamics-sourced black hole. We also show that the motion of photons in this context can be interpreted as nongeodesic curves subjected to a four-force term from the perspective of an observer in the spacetime metric, generalizing previous results in the literature for nonlinear electrodynamics models that depend on a single electromagnetic scalar invariant.