ABSTRACT This paper is aimed at investigating a codimension‐one thick brane with cuscuton dynamics within the framework of modified symmetric teleparallel gravity, where is the nonmetricity scalar and is the energy‐momentum tensor trace. The brane is generated by a scalar field with noncanonical dynamics containing a cuscuton term, which modifies the structure of the scalar sector without introducing additional propagating degrees of freedom. By employing the first‐order formalism, analytical solutions for the scalar field, warp factor, scalar potential, and energy density are obtained for different choices of superpotentials, including sine‐Gordon, polynomial, and linear forms. We analyze how the parameters controlling the nonmetricity corrections and the matter coupling affect the internal structure and localization properties of the brane. In addition, the localization of spin‐ fermions is studied through a minimal Yukawa coupling between the fermionic field and the background scalar field. The resulting Schrödinger‐like equations exhibit a supersymmetric structure that guarantees the stability of the fermionic spectrum and allows the localization of the chiral zero mode on the brane. Furthermore, we investigate the spectrum of massive fermionic modes and identify resonant states through the relative probability method. The appearance of these quasi‐localized modes indicates the presence of metastable fermionic excitations associated with the internal structure of the brane.
ABSTRACT We apply the boundary‐only isothermal formulation of finite‐distance weak gravitational deflection to regular black holes, black‐bounces, traversable wormholes, non‐asymptotically flat backgrounds, and static quadrupolar spacetimes. The methodological advance is not a new value for a known bending angle. It is a metric‐level reduction that removes the Gaussian‐curvature area integral before any particular spacetime is chosen. Local conformal flatness converts the bulk term in the Gauss–Bonnet construction into boundary information from the isothermal conformal factor, while the logarithmic conformal derivative provides a normalization‐invariant input that does not require a photon sphere, a circular null orbit, or an auxiliary calibration radius. At leading weak‐field order, the source and receiver dependence is carried by a reusable set of endpoint functions, whereas the spacetime dependence is carried by the radial expansion of a single boundary datum. This separation is useful when the relevant circular orbit is absent, nonunique, or unrelated to the observed ray, and when asymptotic scattering is unavailable. We demonstrate this scope using Bardeen, Hayward, and Ayón‐Beato–García regular black holes, the Simpson–Visser family, Ellis–Bronnikov and Morris–Thorne wormholes, Schwarzschild–global‐monopole and Mannheim–Kazanas backgrounds, and the equatorial sectors of Zipoy–Voorhees and Erez–Rosen geometries. These applications serve as stress tests and expose a common classification of mass, charge, throat, regular‐core, conical‐background, cosmological‐background, and quadrupolar terms. The present formulation is restricted to static regions with a Riemannian equatorial optical metric and a suitable isothermal covering. The explicit model corrections reported here are leading straight‐ray boundary contributions, not complete higher‐order post‐Minkowskian deflection angles.
We derive an analytic first-order description of how Schwarzschild ringdown affects a detector-based detailed-balance diagnostic in a near-horizon, single-mode setting. A freely falling two-level system couples to a cavity-filtered outgoing mode of fixed asymptotic frequency, whose static Schwarzschild response gives geometric photon statistics and a detailed-balance ratio governed by the surface gravity. We perturb this baseline by an even-parity, axisymmetric quadrupolar quasinormal mode and work in ingoing Eddington-Finkelstein coordinates, which are regular at the future horizon. The perturbation shifts the outgoing eikonal through the double-null contraction of the metric perturbation along the outgoing congruence. After fixing the residual endpoint phase calibration on the cavity worldtube, this redshift-map deformation induces a first-order decaying-oscillatory correction to the detector detailed-balance exponent at the quasinormal frequency. We express the geometric response through a closed boundary formula at the sampling radius and state the adiabatic, narrowband, and linear-response conditions under which the result applies. Detector details, including the gap, switching, and wavepacket profile, enter only through a smooth prefactor, while the ringdown dependence is carried by the quasinormal frequency and calibrated response coefficient. The modulation vanishes in the zero-amplitude, late-time, and stationary quadrupolar limits. The result is not a modification of the Hawking temperature, global Hawking flux, or dynamical horizon thermality, but a controlled correction to an operational detector/cavity detailed-balance observable.
We provide full details of a BV formulation of supergravity in 10 dimensions, to all orders in fermions, built from the generalised geometry description of the theory. In contrast to standard treatments, we introduce neither the degrees of freedom corresponding to orthonormal frames for the metric nor the local Lorentz symmetries that remove them again. Instead, we observe that the field space has a fibred structure, with the fermionic degrees of freedom spanning the fibres. We explain in detail how this geometric picture allows one to understand simultaneous variations of spinorial quantities and the metric with respect to which the spinor bundles are defined. This leads to additional terms in certain commutators on field space which account for the Lorentz transformation terms appearing in the calculation of the supersymmetry algebra. Unencumbered by the Lorentz degrees of freedom, we provide an efficient and full demonstration that our action satisfies the classical master equation.
We apply the Hassan-Sen transformation to the Schwarzschild-Levi-Civita vacuum solution and construct its charged generalization within the low-energy effective field theory of heterotic string theory. Starting from a static, axially symmetric seed metric, we obtain an exact Einstein-Maxwell-dilaton black hole in the Einstein frame and verify explicitly that it satisfies the full set of field equations. The resulting spacetime is characterized by a nontrivial dilaton field, an electric Maxwell field, and a strong angular anisotropy inherited from the Schwarzschild-Levi-Civita geometry. A detailed study of null geodesics reveals the impact of the electric field-dilaton-induced deformation on photon propagation, including the absence of circular photon orbits outside the horizon. In the special massless limit, we uncover the charged Levi-Civita spacetime with a line singularity aligned with the symmetry axis, exhibiting pronounced stretching and squashing behavior in different asymptotic regimes. These results demonstrate that the Hassan-Sen transformation provides a powerful mechanism for generating highly anisotropic charged solutions beyond the standard black hole sector of string-inspired gravity.
A major difficulty in traversable Wormhole (WH) scenario is the necessity of exotic matter arising from the violation of energy conditions within general relativity. This motivates the investigation of modified gravitational frameworks and quantum corrections that may alter the effective stress energy sector and improve the physical viability of such geometries. In this manuscript, we investigate electrically charged traversable WH configurations in linear teleparallel gravity coupled to Euler-Heisenberg nonlinear electrodynamics. A static and spherically symmetric spacetime with a constant redshift function is adopted to obtain an analytic WH solution in which torsion, electric charge, and nonlinear electromagnetic corrections contribute simultaneously to spacetime structure. The physical motivation of this study is that torsion in teleparallel gravity acts as an additional gravitational source, while the Euler-Heisenberg theory represents one loop quantum electrodynamic corrections relevant in strong electromagnetic fields near compact entities. Their combined effect modifies the effective matter distribution and therefore can influence the amount of exotic matter required to support WH throat. We examine geometrical viability conditions, including throat regularity, flaring-out behavior, and asymptotic flatness. The energy conditions are analyzed in detail and reveal parameter regimes where violations are redistributed and significantly weakened due to torsional and nonlinear electromagnetic contributions. A generalized TOV equilibrium analysis demonstrates that hydrostatic, anisotropic, and quantum correction forces can collectively balance each other, allowing static configurations without introducing additional ad hoc matter sources. We further investigate photon motion around WH geometry by studying photon sphere, critical impact parameter, deflection angle, and echo time delay. We show that the nonlinear electromagnetic charge and torsion parameters produce characteristic optical signatures, modifying photon ring size, bending angle, and echo structure, thereby providing potentially observable distinctions from standard compact entities. Therefore, novelty of this work lies in presenting a self-consistent scenario where teleparallel torsion and quantum electrodynamic nonlinearities simultaneously first reduce the exotic matter requirement and second generate observable imprints on light propagation around a horizonless compact configuration.
We explore the connection of positivity of the imaginary part of forward elastic amplitudes for perturbative scattering with consistency of the entanglement generated by the S-matrix, for states with arbitrary internal quantum numbers such as flavor. We also analyze "disentanglers," certain highly entangled initial states for which the action of the S-matrix is to decrease subsystem entanglement. As a by-product, we develop a framework based on wave packets to regularize the spacetime divergences that appear in the plane-wave derivation of the entanglement expression.
In this work, we analyze the - model within the anisotropic electromagnetic-gravitational Ho & rcaron;ava-Lifshitz theory. Starting from the Hamiltonian formulation of the electromagnetic-gravitational-dilaton system in dimensions obtained through a Kaluza-Klein reduction of the Ho & rcaron;ava-Lifshitz theory, we consider the infrared regime with coupling constants , , and the dilaton fixed at its ground state . We show that the Hamiltonian can be written as the Einstein-Maxwell Hamiltonian plus a term proportional to the square of the trace of the canonical momentum . The preservation in time of the Hamiltonian constraint leads to an elliptic equation whose only asymptotically flat solution is , so the Hamiltonian reduces to the Einstein-Maxwell one on the constraint surface . We further analyze the constraint structure and show that the theory propagates four configuration-space physical degrees of freedom, corresponding to the two transverse-traceless gravitational modes and the two transverse electromagnetic modes of Einstein-Maxwell theory. We also show that the condition has a geometrical interpretation as the maximal slicing condition. Under asymptotically flat conditions and without additional boundary constraints, the anisotropic electromagnetic-gravitational Ho & rcaron;ava-Lifshitz theory therefore becomes canonically equivalent to Einstein-Maxwell theory in maximal slicing. Consequently, gravitational and electromagnetic waves far from their sources propagate in exactly the same way in both theories.
We demonstrate that ring-shaped gap solitons can be stabilized in the nonlinear Schr & ouml;dinger equation with saturable nonlinearity and a radially periodic linear lattice, encompassing both fundamental solitons and their vortex counterparts. Two types of solitons, distinguished by different numbers of ring peaks-specifically, single-ring and three-ring solitons, as well as their vortex analogues-are studied. By solving the governing equation, we establish the existence, properties, and stability of these localized solutions, complemented with direct propagation simulations. The power of all these soliton families decreases as the propagation constant increases, satisfying the anti-Vakhitov-Kolokolov criterion for soliton stability. Both stable and unstable examples of soliton propagation are displayed. Although they resemble truncated linear Bloch waves, the profiles of these annular solitons are intriguing, as minor peak rings become evident near the edges of the band gaps, causing instabilities. Notably, the phase profiles of ring-shaped vortex solitons differ from the conventional ones; that is, they exhibit spiraling patterns in the central region that alternate periodically in the radial direction.
Nonmetric and nonholonomic deformations of Einstein-Dirac-Maxwell systems, together with their cosmological implications in metric-affine geometries and modified gravity theories (MGTs), have been explored in a series of recent works; however, classical and quantum information-theoretic interpretations of nonmetric geometries, and their connections to nonstandard particle physics and MGTs, remain largely undeveloped. In this work, we formulate nonmetric geometric and (quantum) information thermodynamic frameworks-referred to as geometric information flows (GIF) and quantum geometric information flows (QGIF)-within which metric-affine gravity models, including f(Q) gravity, can be derived as particular classes of nonmetric Ricci solitons. We introduce generalized definitions and inequalities for relative entropy, mutual information, and entanglement in terms of nonholonomic geometric variables, and show that the corresponding nonmetric geometric flow equations can be decoupled and integrated in generic off-diagonal form using the anholonomic frame and connection deformation method. This formalism enables the explicit construction of exact and parametric solutions and the computation of associated geometric and informational thermodynamic variables, including physically relevant examples describing nonmetric deformations of quasi-stationary black hole-type configurations into locally anisotropic cosmological solutions. We conclude that nonmetric GIF and QGIF thermodynamic variables provide a unifying framework for identifying classes of MGTs suitable for quantum-computational modeling of gravitational and cosmological phenomena, capable of describing accelerating cosmologies and astrophysical objects via off-diagonal configurations in general relativity and extensions such as f(Q) gravity, with further developments to explore connections to quantum information theory through nonmetric generalizations of Perelman's W-entropy.
We investigate Friedmann-Lema & icirc;tre-Robertson-Walker (FLRW) cosmology in the framework of symmetric teleparallel gravity with a nonminimal coupling between dark matter and the gravitational field. In the noncoincidence gauge, the field equations admit an equivalent multi-scalar field representation, which we investigate the phase-space using the Hubble-normalization approach. We classify all stationary points for arbitrary function and we discuss the physical properties of the asymptotic solutions. For the power-law theory, we perform a detailed stability analysis and show that the de Sitter solution is the unique future attractor, while the matter-dominated point appears as a saddle point. Moreover, there exist a family of scaling solutions that can be related to inflationary dynamics. In contrast with uncoupled models, the presence of the coupling introduces a viable matter-dominated era alongside late-time accelerated expansion. Our study shows that the coupling function plays a crucial role in cosmological dynamics in gravity.
This work presents a systematic evaluation of near-zero-error encoding strategies for coherent-state quantum communication, comparing homodyne and threshold detection across alphabet sizes . Simulations were performed for coherent amplitudes and channel transmittance values , enabling a detailed characterization of bit-error rate (BER), optimal operating points, and information-theoretic performance. Threshold detection was found to tend to saturate near for all , consistent with its limited ability to discriminate low-energy coherent states. In contrast, homodyne detection exhibited exponential-like BER suppression, reaching values below for , at and . Error exponent fits further revealed strong scaling behavior, with slopes increasing from 0.8 at to 45 at , suggesting the benefits of redundancy-assisted encoding. Optimal amplitude extraction showed that within the tested grid minimized BER across all loss conditions examined. Capacity proxy evaluation demonstrated that homodyne in these simulations approaches the theoretical limit , achieving bits, while threshold detection remained substantially below capacity. Additional metrics, including and relative BER gain, indicated improvements of up to 2.5 bits and over two orders of magnitude, respectively. All simulations were implemented in Python using PennyLane-Strawberry Fields interfaces, executed entirely on classical hardware to support transparency and reproducibility.
A study of the Wigner functions for massless Dirac fermions in a graphene layer lying in the plane interacting with a homogeneous external magnetic field is provided. Since, at low-energy excitations, the Dirac-Weyl equation is what describes the movement of such charge carriers and is a matrix equation, it is necessary to describe the Wigner function as a matrix function in phase space. By solving the -Dirac-Weyl equation, the Landau levels, as well as the Wigner functions for graphene electrons in the presence of a magnetic field, are obtained.
In this work, we investigate the thermal stability of black holes (BHs) in the presence of thermal fluctuations. We consider a static spherically symmetric nonsingular BH in 4D Einstein-Gauss-Bonnet (EGB) gravity coupled with nonlinear electrodynamics (NED) in an AdS spacetime. We interpret many thermodynamical quantities like temperature, entropy, Helmholtz free energy, internal energy, pressure, enthalpy, Gibbs free energy, and specific heat and interpret how the variations in coupling parameter and NED parameter impact the stability and phase transitions of the BHs. We further examined the distinctive characteristics of BH shadow images observed for different values of both and . The obtained results of BH shadow contours indicate that the increasing values of both and , results in decrease the BH shadow radius significantly. Subsequently, we also investigate the infalling spherical accretion of BH shadows. The results indicate that while variations in relevant parameters do influence the central dark region, the primary factor is the change in observational appearance of the bright photon ring, which appears at the position of the photon sphere.
In this paper, we present an alternative to standard dark energy (DE), where the vacuum energy density (VED) decays and generates the dark matter (DM) via gravitationally induced creation. This decay is considered as an irreversible energy flow maintaining the thermodynamic equilibrium through the constant entropy per particle. Motivated by quantum field theoretic considerations of vacuum decay and adiabatic matter creation, we analyze both the background dynamics and the growth rate of perturbations. The model is confronted with diverse datasets, including cosmic chronometers, Pantheon Type Ia supernovae (SNIa), Baryon acoustic oscillations, cosmic microwave background distance priors, weighted linear growth rate measurements and the local R22 value of , with parameter estimation performed via Markov Chain Monte Carlo (MCMC) methods. Model comparison is performed using the Akaike information criterion (AIC), the Deviance information criterion (DIC), and Bayesian evidence quantified through the Bayes factor. Our results show a consistent transition from a decelerated to an accelerated expansion phase, with present Hubble parameter estimates lying between the Planck and SH0ES values. The structure growth parameter is also compatible with Planck 2018 and recent weak lensing surveys. A thermodynamic analysis confirms consistency with the generalized second law (GSL), and including Casimir contributions provides further insights into the model's dynamics. Overall, the proposed model effectively captures the Universe's evolution at both theoretical and observational levels.
In this study, the cosmological behavior of the Kaniadakis holographic dark energy model is investigated under the theory within the framework of a flat Friedmann-Robertson-Walker (FRW) universe. The generalized holographic energy density based on Kaniadakis entropy is modeled using the Hubble horizon infrared cutoff scale, and the field equations are solved analytically. Using the obtained solutions, the evolution of fundamental cosmological quantities such as the deceleration parameter, the equation of state parameter, and the statefinder parameters as a function of time and redshift is analyzed in detail. It is shown that the model successfully describes the transition to time-accelerated expansion and gives a value of , consistent with current observational data. Furthermore, it is observed that in the statefinder plane, the model exhibits a dynamic dark energy behavior close to the scenario, but tends toward the de Sitter universe in the long term. The results show that the theory of gravity, when considered together with Kaniadakis holographic dark energy, offers a consistent and viable framework for explaining the late-stage accelerating expansion of the universe.
In the Euclidean view, one must first require that positivity not be violated, and from this modest demand, together with locality, a great deal follows: starting from a reflection-positive lattice formulation of pure Yang-Mills theory we obtain a transfer operator with a uniform gap, while large Wilson loops already show an area law by means of convergent character (polymer) expansions; a finite-range, gauge-covariant multiscale analysis then carries these features from one scale to the next with interlaced inequalities whose small defects can be summed, so that exponential clustering and a strictly positive string tension endure in the continuum; the Osterwalder-Schrader reconstruction turns these Euclidean facts into a Minkowski theory with a self-adjoint Hamiltonian, the spectral gap lying above the vacuum and the linear potential for static charges appearing, which gives a concrete picture of confinement; the construction depends on no special regulator, for a single-scale Lipschitz control and a telescoping argument bind all admissible reflection-positive slicings into a unique limiting measure and thus secure universality; moreover, the same framework admits entry from weak coupling, so that the continuum reached from strong coupling meets the one approached along an asymptotically free trajectory, yielding one and the same theory; in my view this is how mathematical clarity and physical insight cooperate: positivity, locality, and renormalization working together so that the mass gap and confinement are not marvels to be assumed, but natural properties of the non-Abelian vacuum.
We perform a late-time cosmological study, we compare the performance of two Dirac-Born-Infeld (DBI) type k-essence scalar field extensions of the model to the standard framework and a scenario using the Chevallier-Polarski-Linder (CPL) equation of state parametrization. We solve background dynamics numerically as functions of redshift and incorporate them into a Bayesian inference pipeline accelerated by machine learning. We use a Flax-based surrogate emulator to replace repeated direct integrations of the ODE system, reducing computational cost. A hybrid scheme that combines stochastic variational inference (SVI) with No-U-Turn Hamiltonian Monte Carlo constrains cosmological parameters using the Pantheon+SH0ES Type Ia supernova sample, DESI BAO (DR2) data, and cosmic chronometer measurements without CMB-based priors. In both DBI k-essence formulations, present-day dark energy equations of state are consistent with cosmic acceleration, indicating a -like regime with a modest redshift dependence. The model is marginally favored by conventional model selection measures such as , AIC, BIC, and DIC, which are based on goodness of fit and penalized. However, Bayesian predictive measures like WAIC and PSIS-LOO show no significant differences between , , and DBI k-essence scenarios. All have similar model weights and out-of-sample predictive performance for the datasets. Thus, DBI k-essence models mimic the success of the classic paradigm while allowing controlled, redshift-dependent deviations from a strict cosmological constant that are consistent with present late-time observations.
This research examines the viability of charged wormhole (WH) geometries in the background of non-metric gravity, characterized through the function, f(Q,T) where non-metricity is defined by Q and trace of stress-energy tensor is represented by T. Adopting the Morris-Thorne spacetime and incorporating Maxwell field equations with an anisotropic fluid configuration, the static spherically symmetric WH structures are analyzed. The modified field equations that capture the gravitational dynamics influenced by non-metricity and matter sources are deduced. Various f(Q,T) models and shape functions with constant redshift are considered to find solutions for traversable WHs. Additionally, the energy conditions for different functional forms to identify viable WH structures are explored. This analysis reveals that traversable WH solutions are possible in this gravitational model, shedding light on the characteristics of spacetime and the potential for creating shortcuts in the universe.
In this work, we have studied bouncing cosmology in f(Q,C) gravity framework. This gravity theory is an extension of f(Q,C) gravity where a boundary term C is also included. We have considered holographic fluid with generalized infrared cut-offs to drive the bounce. For some chosen forms of f(Q,C), we have discussed the bouncing behavior with scale factors derived from the IR cutoffs of some generalized forms of holographic fluid considered as bouncing fluid. We have checked the null-energy condition for our models and also discussed the second law of thermodynamics in this setup. The analysis shows that the models can produce bouncing solutions, which are mathematically consistent and can give possible explanation to the early universe without an initial singularity. The study also indicates that f(Q,C) gravity with generalized cut-offs may be useful to understand cosmic evolution beyond standard Lambda CDM.
