arXiv subjects

Saleh O. Allehabi

Publications and source records attributed to Saleh O. Allehabi.

At least 19 recordsLinked to original sources

arXiv2026

Sneutrino Tribrid Inflation in Flipped $\mathbf{SU(5)}$: Confronting ACT DR6 and Planck Observations

We construct a realization of sneutrino tribrid inflation within the $R$-symmetric flipped $SU(5)$ grand unified theory. A vector-like pair of matter multiplets, $10_V+\overline{10}_V$, provides a $D$-flat inflaton direction along the right-handed sneutrino component, with an additional $Z_2$ symmetry forbidding a direct inflaton mass term so that the leading inflationary interaction is a non-renormalizable Kähler-driven operator. Unlike previous studies, we treat the superpotential cutoff scale $M_s$ as independent of the reduced Planck mass, $m_P$, substantially enlarging the viable parameter space. Confronting the model with the ACT DR6/Planck determination $n_s=0.9734\pm0.0034$ and the $2σ$ bound on the running of the spectral index, we identify broad regions of viable parameter space in which the flipped $SU(5)$ symmetry-breaking scale can approach the conventional GUT scale, $M\simeq M_{\rm GUT}$, and the tensor-to-scalar ratio can reach observable values, $r\gtrsim10^{-3}$, within reach of forthcoming CMB $B$-mode experiment such as LiteBIRD. We further study the post-inflationary dynamics, identifying the inflaton with the lightest right-handed sneutrino in a conventional type-I seesaw sector, whose out-of-equilibrium decay generates a lepton asymmetry that is converted into the observed baryon asymmetry via non-thermal leptogenesis and electroweak sphalerons, for a reheating temperature consistent with both successful leptogenesis and the gravitino constraint.

hep-ph↗

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

Quantum-Conditioned Curvatures in Spacetime Surrounding Kerr-Newmann Black Hole

This research examines the possibility whether the curvatures found in conventional General Relativity (GR) are the only existing ones, using both analytical and numerical techniques. To this end, we introduce a thorough investigation of Riemann curvatures in the spacetime surrounding a Kerr-Newmann black hole, which is distinguished by its specific electric charges and rotational dynamics. We apply a geometric quantization ansatz that centers on the quantization of the metric tensor, from which the complete set of field equations can be derived. The conformal transformation of the standard metric tensor upholds all the principles of GR while also extending its applicability to lower (quantum) scales. We recognize two types of Riemann curvatures. In addition to the positive curvatures present in classical GR formulations, we also find significant negative curvatures at lower (quantum) scales. This may indicate quantum sources of gravitation that classical GR does not seem equipped to explore.

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

Stress-Energy Tensor for Modified General Relativity with Quantum-Deformed Metric in Riemann Spacetime

The generalized noncommutative Heisenberg algebra, which is based on the generalized uncertainty principle, imposes a minimal length uncertainty on quantum mechanics (QM), on one hand. On the other hand, the quantum-induced spacetime which is based on quantum-deformed metric through geometric quantization is proposed as additional curvatures on the relativistic tangent bundle on Finsler manifold. An additional term that incorporates minimal length discretization along with second-order derivatives of tangent covectors, thereby suggesting an approach to reconcile the principles of QM with General Relativity (GR), is utilized for the construction of a torsion-free quantum-deformed metric on Riemann manifold. Consequently, it is proposed that quantum-induced revisions to the symmetric stress-energy tensor, source of spacetime curvature, along with the current density related to the gauge transformations of gravity, ought to be taken into account in the matter Lagrangian with electromagnetic and scalar components. Vanishing covariant derivative of the quantum-induced stress-energy tensor suggests that the corresponding continuity equation implies that the gravitational fields do work on the classical and quantum matter and vice versa and the non-gravitational energy and momentum are no longer entirely conserved. For vanishing tangent covector derivatives and/or minimal length uncertainty, the classical formulations of the Einstein stress-energy tensor are retained and accordingly that of GR and QM. We conclude that the proposed quantum-induced formulation of the stress-energy tensor is fundamentally suitable for both classical and quantum-induced field equations.

gr-qc↗

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↗

arXiv2026

Radiatively Corrected Hybrid Inflation: Parameter Scans and Machine Learning with ACT and Future CMB Experiments

We investigate a realistic non-supersymmetric hybrid inflation model incorporating right-handed neutrinos and assess its viability in light of recent cosmological observations. At tree level, the inflaton potential yields a blue-tilted scalar spectrum, which is disfavored by current data from Planck and ACT that instead support a red tilt. We show that including one-loop quantum corrections, arising from generic couplings required for reheating, significantly modifies the potential, flattening it at large field values. This leads to a red-tilted spectral index ($n_s < 1$) and a suppressed tensor-to-scalar ratio $r$, both consistent with observational constraints. To ensure theoretical control, we focus on sub-Planckian field values, where the effective field theory description remains valid. The coupling of the inflaton to right-handed neutrinos naturally facilitates efficient reheating and enables the generation of the baryon asymmetry via non-thermal leptogenesis. We further explore the model's parameter space using a multi-output random forest classifier, achieving prediction accuracies in the range of $87.5\%$ to $98.9\%$. Our analysis shows that approximately $15\%$ of the parameter space satisfies at least one current experimental constraint, underscoring the essential role of quantum corrections in reconciling particle physics models with precision cosmology, and highlighting the effectiveness of machine learning techniques in probing complex theoretical frameworks.

hep-ph↗

arXiv2026

Revisiting Polynomial Hybrid Inflation: Planck and ACT Compatibility via Radiative Corrections

We investigate the impact of one-loop radiative corrections in a non-supersymmetric model of hybrid inflation with a chaotic (polynomial-like) potential,$V(ϕ) = V_0 + λ_p ϕ^p$, in the light of the latest constraints from \textit{Planck} and \textit{Atacama Cosmology Telescope} (ACT) observations. Here, $V_0$ denotes the energy scale of inflation, and $λ_p$ is a coupling associated with the polynomial term of power $p$. These corrections can naturally arise from couplings of the inflaton to other matter fields, which also facilitate the reheating process. At the tree level, the predictions of such models for the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$ typically lie outside the current observational bounds. However, incorporating one-loop radiative corrections modifies the potential to, \[ V(ϕ) = V_0 + λ_p ϕ^p + A ϕ^4 \ln (ϕ/ μ), \] where $A$ characterizes the strength of the inflaton's coupling to other fields, and $μ$ is an appropriate renormalization scale. This radiatively corrected potential can reconcile the model with the combined \textit{Planck}+ACT data over a suitable range of parameter space explored in this work. In particular, radiative corrections from fermionic loops ($A < 0$) suppress the tensor-to-scalar ratio $r$, while simultaneously yielding a red-tilted spectrum with $n_s < 1$, even for sub-Planckian field excursions. This brings the prediction in line with current observations, while still allowing for potentially detectable signatures of primordial gravitational waves. Furthermore, the inflaton's couplings enable successful reheating and naturally accommodate non-thermal leptogenesis, providing a unified framework for inflation and baryogenesis.

hep-ph↗

arXiv2025

Hf$^{12+}$ ion: Highly Charged Ion for Next-Generation Atomic Clocks and Tests of Fundamental Physics

We use advanced computational techniques to study the electronic structure of the Hf$^{12+}$ ion, with the goal of assessing its potential for use in highly accurate atomic optical clocks and search for new physics. Such clocks should combine low sensitivity to external perturbations with high sensitivity to a possible time variation of the fine-structure constant $α$. The system features two clock transitions. One is an $f-p$ transition in terms of single-electron states, which exhibits strong sensitivity to variations in $α$. The other is an electric-quadrupole (E2) transition between states of the ground-state configuration, which can serve as an anchor transition for measuring one frequency against the other. All three relevant states possess very small and nearly equal static dipole polarizabilities, resulting in an extremely small blackbody-radiation shift. The quadrupole shift is also small and can be further suppressed. Altogether, Hf$^{12+}$ appears to be a highly promising candidate for both precision timekeeping and searches for new physics.

physics.atom-ph↗

arXiv2025

Tribrid Inflation, Type II Leptogenesis, and Observable Gravitational Waves in $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_{B-L}$

We present a concrete realization of tribrid inflation within the framework of the gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_{B-L}$. In this model, inflation is driven by the neutral components of left-handed Higgs triplets, which also play a central role in generating the observed baryon asymmetry of the universe via non-thermal leptogenesis. Tiny neutrino masses arise naturally through a type-II seesaw mechanism, facilitated by right-handed triplet fields. Supergravity corrections, stemming from the leading-order terms in a non-minimal Kähler potential, are essential in bringing the predictions of the scalar spectral index $n_s$ into agreement with the latest cosmological data, including the Atacama Cosmology Telescope Data Release 6, Planck 2018, and LB-BK18. A key feature of this model is the existence of a viable parameter space that predicts potentially observable primordial gravitational waves, with a tensor-to-scalar ratio $r \lesssim 0.005$, placing it within reach of upcoming experiments.

hep-ph↗

arXiv2024

High-accuracy optical clocks with sensitivity to the fine-structure constant variation based on Sm$ ^{10+} $

We identify two metastable excited states in Sm$ ^{10+} $ highly charged ion as candidates for high accuracy optical clocks. Several atomic properties relevant to optical clock development are calculated using relativistic many-body methods. This includes energy levels, transition amplitudes, lifetimes, scalar polarizabilities, black body radiation shift, and the sensitivity to the fine structure constant variation. We found that the clock transitions are not sensitive to perturbation, e.g., relative black body radiation shifts are $\sim 10^{-19}$. The enhancement factor for the $α$ variation is $\sim$ 0.8 for one clock transition and $\sim$ 16 for another.

hep-ph↗

arXiv2023

Prospects for optical clocks combining high sensitivity to new physics with insensitivity to perturbations; the case of Sb$^{+}$, Au$^{+}$, and Hg$^{2+}$

Our study is motivated by the prospect of several metastable states in the Sb$ ^{+} $, Au$ ^{+} $, and Hg$ ^{2+} $ ions being used as possible candidates for optical clocks. We calculate several atomic properties relevant to the development of optical clocks for those clock transitions using two different approaches of relativistic many-body calculations, configuration interaction with single-double coupled-cluster (CI+SD) method, and configuration interaction with perturbation theory (CIPT) method. Our results demonstrate that the relative black body radiation shifts for these transitions are small, $ \sim 10 ^{-16} $. It is also found that there is considerable sensitivity to new physics, as evidenced by a significant enhancement of the effect of the time variation of the fine structure constant $α$ on the frequencies of the clock transitions. The corresponding factor ranges from -5.56 to 2.20. Our results are compared with available previous data.

physics.atom-ph↗

arXiv2023

Calculation of the hyperfine structure of Dy, Ho, Cf, and Es

A recently developed version of the configuration interaction (CI) method for open shells with a large number of valence electrons has been used to study two heavy atoms, californium (Cf, Z= 98) and einsteinium (Es, Z= 99). Motivated by experimental work to measure the hyperfine structure (HFS) for these atoms, we perform the calculations of the magnetic dipole HFS constants $A$ and electric quadrupole HFS constant $B$ for the sake of interpretation of the measurements in terms of nuclear magnetic moment $μ$ and electric quadrupole moment $Q$. For verification of our computations, we have also carried out similar calculations for the lighter homologs dysprosium (Dy, Z= 66) and holmium (Ho, Z= 67), whose electronic structures are similar to Cf and Es, respectively. We have conducted a revision of the nuclear moments of some isotopes of Es leading to an improved value of the magnetic moment of $^{253}$Es [$μ$($^{253}$Es) = 4.20(13)$μ_N$].

physics.atom-ph↗

arXiv2022

High-accuracy optical clocks based on group 16-like highly charged ions

We identify laser-accessible transitions in group 16-like highly charged ions as candidates for high-accuracy optical clocks, including S-, Se-, and Te-like systems. For this class of ions, the ground $^{3}P_{J}$ fine structure manifold exhibits irregular (nonmonotonic in $J$) energy ordering for large enough ionization degree. We consider the $|^3P_2\rangle \longleftrightarrow |^3P_0\rangle$ (ground to first-excited state) electric quadrupole transition, performing relativistic many-body calculations of several atomic properties important for optical clock development. All ions discussed are suitable for production in small-scale ion sources and lend themselves to sympathetic cooling and quantum-logic readout with singly charged ions.

physics.atom-ph↗

arXiv2022

Atomic clocks highly sensitive to the variation of the fine structure constant based on Hf II, Hf IV, and W VI ions

We demonstrate that several metastable excited states in Hf$~$II, Hf$~$IV and W$~$VI ions may be good clock states since they are sufficiently long-living and are not sensitive to the perturbations. Cooling E1 transitions are available. Energy levels, Landé $g$-factors, transition amplitudes for electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transitions, lifetimes, and electric quadrupole moments for Hf$~$II, Hf$~$IV, and W$~$VI ions are investigated using a combination of several methods of relativistic many-body calculations including the configuration interaction (CI), linearized coupled-cluster single-doubles (SD) and many-body perturbation theory (CI+SD), and also the configuration interaction with perturbation theory (CIPT). Scalar polarizabilities of the ground states and the clock states have been calculated to determine the black body radiation (BBR) shifts. We have found that the relative BBR shifts for these transitions range between 10$^{-16}$ $-$ 10$^{-18}$. A linear combination of two clock transition frequencies allows one to further suppress BBR. Several $5d$ - $6s$ single-electron clock transitions ensure high sensitivity of the transition frequencies to the variation of the fine structure constant $α$ and may be used to search for dark matter producing this variation of $α$. The enhancement coefficient for $α$ variation reaches $K=8.3$. Six stable isotopes of Hf and 5 stable isotopes in W allow one to make King plots and search for new interactions mediated by scalar particles or other mechanisms.

physics.atom-ph↗

arXiv2021

Theoretical study of electronic structure of hafnium (Hf, Z=72) and rutherfordium (Rf, Z=104) atoms and their ions: Energy levels and hyperfine structure constants

Energy levels, magnetic dipole, and electric quadrupole hyperfine structure of the superheavy element rutherfordium (Rf, $Z$=104) and its first three ions are calculated using a combination of the configuration interaction, coupled-cluster single-doubles, and many-body perturbation theory techniques. The results are to be used in future interpretations of the measurements in terms of nuclear magnetic dipole and electric quadrupole momenta. To have a guide on the accuracy of the study, we perform similar calculations for hafnium (Hf, $Z$=72) and its ions. Hf is a lighter analog of Rf with a similar electronic structure. Good agreement with the experiment for Hf and with available previous calculations of the energy levels of Rf is demonstrated.

physics.atom-ph↗