A set of $3+1$ equations for stochastic inflation incorporating all metric and scalar matter degrees of freedom, first presented in previous work Launay et al. [Phys. Rev. D 109, 123523 (2024).], are rederived in a gauge invariant manner. We then present numerical implementations of these stochastic equations, cast in the Baumgarte-Shapiro-Shibata-Nakamura formulation of numerical relativity, demonstrating their efficacy in both a slow-roll and an ultra slow-roll scenario. We find the evolution is correctly reproduced for all the dynamical variables, and the energy and momentum constraints are well satisfied. This demonstrates that the stochastic equations are theoretically and numerically robust and ready to be applied to a wider inflationary landscape. Our simulations result in real space realizations of the fully nonlinear stochastic dynamics with gradients and anisotropic expansion retained. This work generalizes standard stochastic inflation, inflationary numerical relativity, and lattice cosmology, opening up the possibility for reliable predictions of nonperturbative phenomena and providing precise initial conditions for subsequent cosmological eras.

Although well studied, our understanding of the mass ejection mechanisms of cataclysmic variables remains incomplete. Recent work suggests that binary interaction plays an important role in driving and shaping this mass ejection and may affect the long-term evolution of the system. In this paper, we perform a three-dimensional moving-mesh hydrodynamic simulation of a cataclysmic variable system to study the effect of binary interaction on mass ejection. We find that once the flow crosses the ${\mathrm{L}}_1$ Lagrange point, the material is ejected roughly isotropically. This can be seen in a roughly spherical distribution of the ejecta at large radii. We also show that the ${\mathrm{L}}_2$ Lagrange point is not important in the ejection of mass, contrary to the assumption in some previous work in this area. Finally, we find that the specific angular momentum of the ejected material is larger than its initial specific angular momentum. This enhanced angular momentum ejection likely affects the long-term evolution of the binary system.

Mergers of white dwarf binaries are a possible progenitor channel for Type Ia supernovae. While white dwarfs are abundant in the Universe and relatively well understood, their gravitational wave signals have not yet been directly observed. In order to detect gravitational waves from merging white dwarf binaries, a detector in the mid-band between LIGO-Virgo-KAGRA and LISA appears necessary. In this paper, we compute and discuss the gravitational waves emitted by inspiraling and merging white dwarf binaries, and assess their detectability with proposed space-based atom-interferometer detectors such as MAGIS Space and AEDGE. Gravitational waves from massive white dwarf binaries can be observed for many years before merger, offering a unique early warning of their final explosion. Our projections suggest that MAGIS Space could detect signals from Type Ia supernova progenitors at least once every four years, while AEDGE could observe at least a few hundred such events annually. The prolonged gravitational wave emission captured by atom interferometers provides precise sky localization and can allow observation of the final explosion with electromagnetic telescopes. The combined observation with electromagnetic radiation from the white dwarf binary coalescence could open a new pathway for multimessenger astronomy involving some of the brightest transient events in the Universe.

Teleparallel Born-Infeld gravity (TBI) is a modified theory of gravity that aims to maintain second-order field equations, leading to alternative scenarios for strong gravity and cosmological settings. In this study, we examine the impact of TBI gravity on the physical characteristics of thin (Novikov-Thorne) accretion disks, focusing on quantities such as flux, pressure, temperature, etc. We also examine the spectral luminosity, comparing it to disks around the Schwarzschild black holes. By comparing the theoretical predictions to observational data in the low frequency regime, we demonstrate the model’s ability to match real astrophysical systems and distinguish subtle differences between TBI gravity and general relativity, with improved sensitivity. Furthermore, the results suggest that observations of x-ray spectra from the inner disk regions can provide valuable insights into the properties of TBI gravity, potentially offering constraints on this modified gravity theory through future astrophysical observations.

We present a next-to-leading-order (NLO) analysis of the rare radiative decay ${\eta }_b\to J/\psi \gamma$ within the framework of nonrelativistic QCD. We systematically compute the complete $\mathcal{O}({\alpha }_s)$ corrections, which include the one-loop QCD corrections to the QED-initiated amplitudes and the two-loop corrections to the QCD-initiated ones. The branching ratio is enhanced from ${2.06}_{-1.32}^{+2.82}\times {10}^{-7}$ at leading order to ${7.53}_{-1.16}^{+5.67}\times {10}^{-7}$ at NLO, representing an increase by a factor of about 3.65. The theoretical uncertainties caused by renormalization scale and $m_{b/c}$ masses are also discussed. Furthermore, the renormalization scale dependence is reduced at NLO.

An interesting framework to achieve gauge coupling unification consists in adding to the Standard Model Lagrangian nonrenormalizable operators of $d\ge 5$, which affect the kinetic term of gauge fields. We first review the phenomenology related to this framework in the context of $SU(5)$, identifying which are the most interesting representations for the sake of achieving coupling unification. Second, we point out that in the case of a dynamical breaking pattern, it is possible to relate gauge coupling unification with the doublet-triplet splitting problem. We show that condensates of fermions in the 5 representation do not lead to viable models because of proton decay constraints. At difference, we point out that successful models can be obtained by considering condensates of fermions in the 10, as well as in the 24 representations.

Loops of portal matter (PM) fields carrying both dark and Standard Model (SM) quantum numbers can lead to the kinetic mixing (KM) of the SM photon and the analogous dark photon (DP) of a phenomenologically interesting magnitude. However, in specific frameworks, different loops of these same PM fields can also lead to other new types of interactions between some of the SM fields and the DP via the generation of “dark moment”-like couplings, even though the SM fields carry a zero dark charge at tree level. In recent work, this possibility has been explored for the case when these SM fields are fermionic. In this paper, we extend this idea to the case of the SM $W$ boson, employing a previously examined model wherein PM consists of a complex scalar triplet plus a complex singlet, both of which obtain vacuum expectation values and thus also generate the DP mass. While this setup results in a somewhat stronger interaction between the DP and the $W$ than in the familiar KM setup, the rate for $W+\mathrm{DP}$ production at the LHC is shown to still be rather small and is very difficult to observe due to large SM backgrounds. The direct production of the scalar PM itself, however, is shown to lead to similar new physics signatures but with much larger rates, and are considered here in their own right. The properties of such new PM states may already be constrained by LHC searches in both the $W^{\pm }+$ missing transverse energy (MET) and $W^{+}{W}^{-}+\mathrm{MET}$ channels.

We consider the hypothetical possibility of neutral gauge bosons ($Z^{\prime }$) with flavor-specific leptophilic couplings. For such New Physics (NP) interactions, the current experimental constraints are much more relaxed in the heavy mass regime, particularly for masses $\ge \mathcal{O}(1)\mathrm{TeV}$. However, in the presence of a leptophilic $Z^{\prime }$, leptonic decay modes of the electroweak gauge bosons and Higgs can be corrected at the loop level. Using the existing upper bounds on the corresponding decay widths, we find that one can impose stronger exclusion limits on the interactions of a heavy $Z^{\prime }$. Future updates on the aforesaid decay channels can be used in complementarity with the proposed lepton colliders to probe even weaker leptophilic NP interactions at the TeV scale and beyond.

The “practical Dirac-Majorana confusion theorem” (PDMCT) asserts that phenomenological differences between Dirac and Majorana neutrinos are kinematically suppressed by $(m_{\nu }/E{)}^2$ in lepton-number-conserving processes. The PDMCT relies on standard left-handed neutrino interactions, as in the Standard Model, in which case Dirac and Majorana neutrinos are experimentally indistinguishable in lepton-number-conserving processes. Our scenario explicitly goes beyond these assumptions by introducing a neutral vector boson $Z^{\prime }$ with $CP$-violating, flavor-changing neutral current (FCNC) couplings, which generate observable Dirac-Majorana differences while remaining fully consistent with the PDMCT. In strict accordance with the PDMCT, Fermi-Dirac statistics dictate that the flavor-diagonal vector current identically vanishes for Majorana neutrinos. For nondiagonal transitions, the Majorana condition strictly forbids the real ($CP$-conserving) component of the vector interaction, leaving only an imaginary coupling. As a consequence, the observable difference in inclusive scattering cross sections between Dirac and Majorana neutrinos is driven entirely by the FCNC $CP$-violating couplings. We apply these results to coherent elastic neutrino-nucleus scattering, showing that for spin-zero targets, the distinguishability of the neutrino’s nature is determined by the $CP$ structure of the new interaction.

We consider the degenerate minima arising from scalar potentials invariant under $\mathrm{\Sigma }(36\times 3)$, or under its subgroups $\mathrm{\Delta }(54)$ and $\mathrm{\Delta }(27)$ (with or without imposed $CP$ symmetries), for a triplet of those symmetries. In this framework, we classify the distinct domain walls between the degenerate minima and calculate the respective tensions.

The interactions of dark matter with Standard Model particles can be systematically studied in the language of effective field theories. We investigate dark matter interactions with Standard Model particles, including spin-dependent interactions, for direct detection experiments and demonstrate that, although the scattering rate generally depends on multiple types of material response functions, certain linear combinations of these material response functions vanish if the initial and final electronic states share the same Hamiltonian. We also find that several other response functions vanish in parity-symmetric materials, making these systems as simple as isotropic detectors in some respects. Finally, we present the scattering rate for an anisotropic, possibly chiral detector, for generic dark matter-electron spin interactions. These relations reduce the number of independent response functions needed, thereby simplifying the computational complexity for a broad class of dark matter models. Our results provide a complete and efficient toolkit for analyzing electron recoil signals in diverse detector materials.

We investigate the phase structure of the ($1+1$)-dimensional single-flavor Gross–Neveu model with Wilson fermions using the Grassmann corner transfer matrix renormalization group (CTMRG). The path integral is formulated as a two-dimensional Grassmann tensor network and approximately contracted by the Grassmann CTMRG algorithm. We investigate the phase diagram by varying the fermion mass and the four-fermion coupling, using the pseudoscalar condensate as an order parameter for the ${\mathbb{Z}}_2$ parity symmetry breaking phase. The universality classes of the phase boundaries are identified through the central charge $c$ obtained via scaling analysis of the entanglement entropy. Furthermore, we extract the quantity related to the entanglement spectrum from the converged CTMRG environments, allowing us to distinguish the topological insulator phase and the trivial phase. The resulting phase structure suggests that the Aoki phase is separated from the other phases by critical lines characterized by $c=1/2$, while the critical lines with $c=1$ separate the topological insulating and trivial phases. Our numerical results also indicate that the Aoki phase does not persist in the strong-coupling regime for the single-flavor theory.

In this work, we perform a comprehensive phenomenological analysis of the exotic hadronic states $Z_c(3900)$, $Z_c(4020)$, $Z_b(10610)$, and $Z_b(10650)$ within the framework of heavy quark spin symmetry (HQSS) and its violation. By constructing $S$-wave contact interactions between elastic ($D{\overline{D}}^{*}/D^{*}{\overline{D}}^{*}$ or $B{\overline{B}}^{*}/B^{*}{\overline{B}}^{*}$) and inelastic ($J/\psi \pi ,h_c\pi$ or $\mathrm{\Upsilon }\pi$, $h_b\pi$) channels, we solve the Lippmann-Schwinger equation to obtain physical production amplitudes and perform a global fit to experimental invariant-mass spectra. Our results demonstrate a striking difference between the charm and bottom sectors: HQSS violation is negligible in the bottom system, leading to comparable peak structures for both $Z_b$ states in all hidden-bottom decay channels. In contrast, significant HQSS breaking is required to describe the $Z_c$ system, where the violation is predominantly concentrated in the elastic interactions. This explains the observed selectivity: $Z_c(3900)$ appears prominently only in $J/\psi \pi$, while $Z_c(4020)$ appears only in $h_c\pi$. Regardless of whether HQSS violation is taken into account, both the $Z_b(10610)$ and $Z_b(10650)$ poles can appear near the $B{\overline{B}}^{*}$ and $B^{*}{\overline{B}}^{*}$ thresholds, respectively. In the hidden charm sector, however, only the framework that includes HQSS violation can successfully describe the experimental data, leading to a single pole around the $D{\overline{D}}^{*}$ threshold, which is identified as the $Z_c(3900)$. Meanwhile, the structure associated with the $Z_c(4020)$ is interpreted as a cusp effect. The robustness of our model is verified against variations of the form factor and cutoff, showing stable results.

We study the pseudoscalar ($J^{PC}=0^{-+}$) and vector ($1^{--}$) top-antitop (toponium) systems within the rainbow-ladder truncation of the Dyson-Schwinger and Bethe-Salpeter equations, employing the Qin-Chang effective interaction. After validating the framework in the charmonium and bottomonium sectors, we extend it consistently to the top sector, incorporating renormalization-group running of the current quark mass and a careful treatment of the number of active flavors. We compute masses and leptonic decay constants for $N_f=5$ and 6, then analyze their dependence on the renormalization scale in the range $\mu =400–800\mathrm{GeV}$. The resulting toponium masses lie near 344–346 GeV with hyperfine splittings below 0.14–0.17 GeV, while the decay constants are large, 6–7 GeV, and exhibit the expected heavy-quark scaling behavior. We find only mild sensitivity to the renormalization point and a systematic reduction of binding when increasing $N_f$. Although the physical top quark decays weakly before hadronization, our results demonstrate that, within a Poincaré-covariant nonperturbative framework, quantum chromodynamics (QCD) generates tightly correlated pseudoscalar and vector toponium systems in that extreme heavy-quark limit.

A search for the pair production of heavy spin-$1/2$ or spin-$3/2$ resonances ($t^{*}$) in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ is presented. Data collected with the CMS detector at the CERN LHC from 2016 to 2018 corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$ are used. The analysis targets benchmark signal scenarios where one $t^{*}$ decays into a top quark ($t$) and a photon ($\gamma$), and the other into a $t$ quark and a gluon ($g$), i.e., $pp\to t^{*}\overline{t^{*}}\to tt\gamma g$. All-hadronic final states from the $t$ pair decay chain are selected using jet substructure techniques. The signal is probed as a function of the $t^{*}$ candidate mass, which is reconstructed using the photon and a top quark candidate jet. No significant deviation from the background-only hypothesis is found. Observed (expected) upper limits on the signal cross section at 95% confidence level are set, excluding masses of spin-$1/2$ $t^{*}$ particles below 930 (930) GeV and spin-$3/2$ $t^{*}$ particles below 1330 (1390) GeV. This analysis marks the first search for heavy resonances in the $t\overline{t}\gamma g$ channel. Exploiting the high-energy photon to reduce the backgrounds, this search achieves sensitivity competitive with $pp\to t^{*}\overline{t^{*}}\to t\overline{t}gg$ searches for spin-$1/2$ $t^{*}$ despite the small expected $t^{*}\to t\gamma$ branching fraction.

We study the double cone geometry proposed by Saad-Shenker-Stanford in de Sitter space. We show that with the inclusion of static patch observers, the double cone leads to a linear ramp consistent with random matrix behavior, where the ramp comes from the relative timeshift between two clocks sitting at opposite static patches.

We present an analytical study of the transport coefficients associated with the shear sector of gravitational perturbations around asymptotically anti–de Sitter black branes. In the long-wavelength, low-frequency limit, the wave solutions admit a structure that is fully described in terms of multiple polylogarithms in several variables. We focus primarily on computing the coefficients of the dispersion relation for $\mathcal{N}=4$ super Yang-Mills theory, by performing a bulk computation in the five-dimensional black hole background up to order ${\mathfrak{q}}^{10}$, which extends the results previously available in the literature. We then generalize the procedure to $d+1$ dimensions, characterizing the mathematical structure of the resulting transport coefficient expressions.

The dark bubble model makes a positive cosmological constant natural in string theory, and predicts several new physical phenomena within reach in the near future. In this paper we study the experimental consequences of the model for the strength of gravity at scales of order ${10}^{-5}\mathrm{m}$. Contrary to other models of gravity involving extra dimensions, the dark bubble model predicts gravity to become weaker rather than stronger at small scales, compared to Newtonian gravity. In particular, we provide explicit predictions of measurable deviations using table top experiments. We also show how the same effect reduces the effective force of gravity at high-energy densities in cosmology, leading to a period of early inflation without the need for anything beyond radiation. We also discuss the quantum origin of the Universe with a 5D black hole acting as a catalyst for the nucleation of the dark bubble and how it accounts for the present matter content in the Universe. This leads to a prediction of ${\mathrm{\Omega }}_c\approx 5\times {10}^{-4}$ for a positive curvature of the Universe, suggesting an explanation of the why-now-problem of the cosmological constant. We end by speculating on how to incorporate AdS black shells as black hole mimickers within the dark bubble model.

We develop a basis-covariant one-loop renormalization framework for two interacting real scalars in $D=4-\epsilon$ with the most general parity even two-derivative Lorentz-violating quadratic form, allowing anisotropic spatial gradients and direction-dependent kinetic mixing, together with general cubic and quartic interactions and the relevant lower-dimensional operators forming a renormalization group complete set of operators at one-loop. In dimensional regularization with minimal subtraction we compute the full set of one-loop UV divergences and obtain closed beta functions for quartic and cubic couplings, masses, and linear couplings. The pole coefficients admit a universal spectral representation as angular averages over the direction-dependent eigenvalues and projectors of the UV kinetic matrix; all anisotropy dependence enters through a single universal kernel admitting two-particle phase-space interpretation. We classify fixed points and fixed manifolds and show, in particular, that anisotropy restricts the existence of the coupled Wilson-Fisher-type fixed point. When the cross-gradients are turned on, the coefficients in beta functions are governed by six phase-space weights admitting interpretation in terms of encoding “populations” and “coherences” of the UV normal modes.

We study interacting scalar field theories in which different fields propagate with inequivalent spatial kinetic tensors, corresponding to different sound speeds in different directions. We derive the exact elastic two-body unitarity relation and show that the phase space defines a positive kernel on the sphere, so that the scattering amplitude acts as an operator in angular-momentum space. The corresponding unitarity bounds constrain the eigenvalues of the phase-space-rescaled amplitude. In the weak-anisotropy regime, we obtain the leading correction explicitly and show that it induces $s-d$ mixing. For a two-scalar quartic model, we verify the anisotropic optical theorem at one loop and derive coupled channel elastic unitarity bounds. We also compute the local one-loop effective potential and analyze the corresponding one-loop renormalization-group structure. In the classically scale-invariant limit, the Gildener-Weinberg flat direction is unchanged, whereas anisotropy modifies the radiatively generated scalon mass. In the isotropic but unequal-velocity limit, several results become analytic and the RG flow exhibits an additional invariant ray.