arXiv subjects

Azzah A. Alshehri

Publications and source records attributed to Azzah A. Alshehri.

6 recordsLinked to original sources

arXiv2026

Chiral Phase Structure and In-Medium Modifications of Charmed Meson Masses within SU(4) extended Linear-Sigma Models

We extend the Polyakov-loop-enhanced linear-sigma model to encompass four flavors and utilize it to analyze the light, strange, and charmed meson mass spectrum as it transitions from the vacuum into a hot and dense medium. Within the mean-field approximation, we determine the masses of scalar ($0^{++}$), pseudoscalar ($0^{-+}$), vector ($1^{--}$), and axial-vector ($1^{++}$) meson states, encompassing both open- and hidden-charm constituents, as functions of temperature $T$ and baryon chemical potential $μ_B$. With parameters calibrated to the vacuum spectrum, the charm degree of freedom proves essential for an accurate description of observed masses, and charmed states acquire their in-medium modifications from the light and strange condensates that modify their valence quarks. Each species seems to undergo melting along its distinct trajectory, yet all transitions occur within a narrow band surrounding the chiral transition. The open-charm $D$-meson functions as a precise indicator of chiral restoration: its mass increases substantially across the transition and reflects the non-strange condensate, whereas hidden-charm states remain largely unaffected and serve as reference standards for the surrounding matter. We establish that transition points from three independent measurements delineate the chiral phase boundary ($T_c$, $μ_B$), whose curvature matches lattice-QCD predictions and which persists as a crossover throughout the examined range, exhibiting no critical endpoint.

hep-ph↗

arXiv2026

Quantum-Deformed Phase-Space Geometry and Emergent Inflation in Effective Four-Dimensional Spacetime

We develop a phase-space approach to quantum-deformed gravity. Reducing it to an effective four-dimensional spacetime structure facilitates reanalyzing cosmic inflation and quantum gravity dynamics. Initiated on a cotangent bundle, the gravitational Hamiltonian is then deformed by a zero-homogeneous scalar determined by projective momentum directions and quantum phase-space properties, forming an anisotropic Hamilton geometry on a non-null conic domain. Through section-pullback procedures, an effective spacetime metric is derived, which in the homogeneous and isotropic sector reduces to a conformally deformed FLRW geometry governed by a scalar deformation field. The corresponding modified Einstein, Klein-Gordon, geodesic-deviation, and Raychaudhuri equations are derived and then utilized to construct inflationary background dynamics, slow-roll regimes, e-folds, and perturbation spectra. The framework shows that leading inflationary corrections stem from phase-space deformation and its time dependence, whereas canonical quantization of cosmological perturbations remains standard following background redefinitions. Ultimately, this model establishes a covariant link between quantum-deformed phase-space geometry and effective four-dimensional inflationary dynamics, demonstrating that quantum gravity effects can be encoded as projective phase-space deformations while preserving the classical limit and standard perturbative structure.

gr-qc↗

arXiv2026

The Derivation of Phase-Space Metric in a Geometric Quantization Approach: General Relativity with Quantized Phase-Space Metric and Relative Spacetime

Various extensions to Riemann geometry have been proposed since the inception of general relativity (GR). The aim has been and continues to be to construct a quantum and dynamic spacetime that incorporates the well-known classical (static) spacetime. Apparently, this seems to enable the principles of GR and quantum mechanics (QM) to be reconciled into a coherent relativity and quantum theory. A canonical geometric quantization approach that presents kinematics of free-falling quantum particles within a tangent bundle, expands QM to incorporate relativistic gravitational fields, and generalizes the four-dimensional Riemann manifold into an eight-dimensional one likely discretizes, if not fully quantizes, the Finsler and Hamilton structures. The Finsler and Hamilton metrics can be directly derived from the Hessian matrix. As introduced in [Physics, 7 (2025) 52], the quantized four-dimensional metric tensor can be deduced by means of approximations including proper parameterization of coordinates and the equating line elements on all these manifolds including Riemann manifold. This research, on the contrary, goes beyond all these approximations and proposes the incorporation of a phase-space metric tensor into GR. The derivation of a quantized eight-dimensional metric tensor is not only presented, but also the implications of it and the corresponding relative spacetime are examined.

physics.gen-ph↗

arXiv2026

Temperature Dependence of the Masses of Various Meson States: A Comparative Study in SU(3) and SU(4) extended Linear-Sigma Model

In the extended Linear-Sigma Model (eLSM), the chiral phase structure of meson states, including pseudoscalars ($J^{pc}=0^{-+}$), scalars ($J^{pc}=0^{++}$), vectors ($J^{pc}=1^{--}$), and axial-vectors ($J^{pc}=1^{++}$), is investigated with the mean-field approximation. A systematic comparison between SU(3) and SU(4) configurations is provided. It has been found that the estimations of meson masses derived from SU(4) eLSM are more congruent with experimental values than those derived from SU(3) eLSM. Consequently, we conclude that an increase in quark degrees of freedom significantly enhances the accuracy of meson mass simulations. We investigate the effect of temperature on the masses of various meson states calculated in the SU(3) and SU(4) eLSM. After establishing all the fitting parameters, the temperature dependence of meson masses shows that although various meson states exhibit unique patterns in their mass changes with temperature, they all seem to share a similar range of dissolution temperatures. This means that the critical temperature that marks the phase transition from hadrons to quarks appears to vary slightly depending on the meson states. In this regard, we find that the quarkonium states, formed by a quark and its antiquark, are largely unaffected by variations in the temperature.

hep-ph↗

arXiv2026

Reevaluation of Inflationary Dynamics in Extended General Relativity with Perturbatively and Tensorially Structured Conformal Metric

Based on the conventional metric tensor and driven by a nearly constant energy density, cosmic inflation, characterized by a remarkably accelerated expansion, was proposed as an early epoch in the Universe. The energy density is typically modeled through a slow-rolling scalar field, whose potential energy dominates the dynamics. This mechanism addresses horizon, flatness, and relic problems, while also generating quantum fluctuations that are stretched to cosmological scales, leading to emergence of primordial curvatures and tensor perturbations. Despite its empirical success, significant questions remain regarding identity of the inflaton, origin of the potential, and role of quantum gravity. A quantum-deformed conformal metric that is both perturbatively and tensorially structured and expanded is employed to reexamine the dynamics of inflation, thus enabling the computation of a range of inflationary observables in presence of quantum-induced corrections. We have established a closed and internally consistent set of analytical formulas for scalar and tensor power spectra, including their spectral tilts, runnings, and the tensor-to-scalar ratio, among other parameters. The quantum corrections appear to provide a clear physical interpretation related to measure scaling and momentum-induced kinetic deformation, which facilitates modifications to the inflationary observables in a controlled and predictive manner. While maintaining the classical limits, these corrections provide a well-defined phenomenological perspective on potential quantum-gravitational structures in the early Universe.

gr-qc↗

arXiv2025

Expansion Evolution of Nonhomogeneous Metric with Quantum-Mechanically Revisited Fundamental Metric Tensor

To explore the properties of space and initial singularities in the context of general relativity, where spacetime becomes poorly defined and no longer belongs to a regular manifold, we examine the evolution of the expansion of timelike geodesic congruences for two distinct formulations of the fundamental metric tensor. This analysis is conducted within a nonhomogeneous, anisotropic, and spherically symmetric cosmic background. The results derived from the conventional metric tensor, the building block of Einstein's theory of general relativity, are compared with those obtained from a quantum-mechanically revisited metric tensor. This comparison enables an assessment of the proposed geometric quantization, particularly in terms of whether singularities are regulated or diminished. Utilizing a quantum geometric approach, the numerical analysis incorporating a quantum-mechanically revisited metric tensor applies a mean-field approximation on the integrated quantum operators. In contrast to the results obtained with conventional metric tensor, the quantum-mechanically induced revision of the metric tensor seems to provide a framework for controlling singularities in the new formulation of general relativity. The degree of quantization likely influences the ability to regulate or even potentially remove both singularities. We also conclude that the proposed geometric quantization provides a means to explore the quantum nature of spacetime curvatures, emphasizing that the singularity dilemma arose primarily from the standard semi-classical approximation of Einstein's general relativity.

gr-qc↗