arXiv subjects

Abdel Nasser Tawfik

Publications and source records attributed to Abdel Nasser Tawfik.

At least 37 records · Page 2Linked to original sources

arXiv2022

Particle ratios with in Hadron Resonance Gas (HRG) and Artificial Neural Network (ANN) models

Comparison between various particle ratios such as $K^-/K^+$, $π^-/π^+$, $\bar{p}/p$, $\barΛ/Λ$, $\barΣ/Σ$, $ \barΩ/Ω$, $K^+/π^+$, $K^-/π^-$, $\bar{p}/π^-$, $p/π^-$, $Λ/π^-$, and $Ω/π^-$ calculated using the HRG model with the results estimated from simulation and training of the ANN model in the presence of different experiments measurements such as AGS, SPS, RHIC and LHC energies is done. The success of ANN simulation model to describe the results from both phonological (HRG) model and experimental data will encourage to use it in various predictions for other particle ratios in regions where is no experiments.

hep-ph↗

arXiv2021

Minimal length discretization and properties of modified metric tensor and geodesics

We argue that the minimal length discretization generalizing the Heisenberg uncertainty principle, in which the gravitational impacts on the non--commutation relations are thoughtfully taken into account, radically modifies the spacetime geometry. The resulting metric tensor and geodesic equation combine the general relativity terms with additional terms depending on higher--order derivatives. Suggesting solutions for the modified geodesics, for instance, isn't a trivial task. We discuss on the properties of the resulting metric tensor, line element, and geodesic equation.

physics.gen-ph↗

arXiv2021

Reliable Equations of State of Viscous Strong and Electroweak Matter

For the first time, a reliable estimation for the equations of state (EoS), bulk viscosity, and relaxation time, at temperatures ranging from a few MeV up to TeV or energy density up to $10^{16}~$GeV/fm$^3$. This genuine study covers both strong and electroweak epochs of the early Universe. Non--perturbation (up, down, strange, charm, and bottom quark flavor) and perturbative calculations (up, down, strange, charm, bottom, and top quark flavors), are phenomenologically combined, at vanishing baryon--chemical potential. In these results, calculations from Polyakov linear--sigma model (PLSM) of the vacuum and thermal condensations of the gluons and the quarks (up, down, strange, and charm flavors) are also integrated. Furthermore, additional degrees of freedom (photons, neutrinos, charged leptons, electroweak particles, and scalar Higgs boson) are found significant along the entire range of temperatures. As never done before, the present study brings the standard model of elementary particles closer to the standard model for cosmology.

hep-ph↗

arXiv2021

Bulk viscosity in strong and electroweak matter

For temperatures $T$ ranging from a few MeV up to TeV and energy density $ρ$ up to $10^{16}~$GeV/fm$^3$, the bulk viscosity $ζ$ is calculated in non-perturbation (up, down, strange, charm, and bottom) and perturbation theories with up, down, strange, charm, bottom, and top quark flavors, at vanishing baryon-chemical potential. To these calculations, results deduced from the effective QCD-like model, the Polyakov linear-sigma model (PLSM), are also integrated in. The PLSM merely comes up with essential contributions for the vacuum and thermal condensations of the gluons and the quarks (up, down, strange, and charm flavors). Furthermore, the thermal contributions of the photons, neutrinos, charged leptons, electroweak particles, and scalar Higgs boson, are found very significant along the entire range of $T$ and $ρ$ and therefore could be well integrated in. We present the dimensionless quantity $9 ω_0 ζ/Ts$, where $ω_0$ is a perturbative scale and $s$ is the entropy density and conclude that $9 ω_0 ζ/Ts$ exponentially decreases with increasing $T$. We also conclude that the resulting $ζ$ with the non-perturbative and perturbative QCD contributions non-monotonically increases with increasing $ρ$. But with nearly-entire standard model contributions considered in the present study, $ζ$ almost-linearly increases with increasing $ρ$. Apparently, these results offer a great deal to explore in astrophysics, cosmology, and nuclear collisions.

hep-ph↗

arXiv2021

Particles Multiplicity Based on Rapidity in Landau and Artificial Neural Network(ANN) Models

ANN model is used to estimate the multiplicity per rapidity for charged pions and kaons observed in various high-energy experiments from central Au+Au collisions with energies ranging from 2-200 GeV, and then compared to available experimental data, including RHIC-BRAHMS, and the future facilities at NICA and FAIR. We also used Landau hydrodynamical approach, which has a better describtion for the evolution of hot and dense matter produced in ultra-relativistic heavy-ion collisions. The approach is fitted to both results estimated from experiment and ANN simulation. We noticed that the Landau model accurately reproduces the entire range of multiplicity per rapidity for all created particles at all energies. Also ANN model can reproduce the multiplicity per rapidity very well for all considered particles.

hep-ph↗

arXiv2021

Chiral magnetic properties of QCD phase-diagram

The QCD phase diagram is studied, at finite magnetic field. Our calculations are based on the QCD effective model, the SU($3$) Polyakov linear sigma model (PLSM), in which the chiral symmetry is integrated in the hadron phase and in the parton phase, the up-, down- and strange-quark degrees of freedom are incorporated besides the inclusion of Polyakov loop potentials in the pure gauge limit, which are motivated by various underlying QCD symmetries. The Landau quantization and the magnetic catalysis are implemented. The response of the QCD matter to an external magnetic field such as magnetization, magnetic susceptibility and permeability has been estimated. We conclude that the parton phase has higher values of magnetization, magnetic susceptibility, and permeability relative to the hadron phase. Depending on the contributions to the Landau levels, we conclude that the chiral magnetic field enhances the chiral quark condensates and hence the chiral QCD phase diagram, i.e. the hadron-parton phase transition likely takes place, at lower critical temperatures and chemical potentials.

hep-ph↗

arXiv2021

Early Universe Thermodynamics and Evolution in Nonviscous and Viscous Strong and Electroweak epochs: Possible Analytical Solutions

Based on recent perturbative and non-perturbative lattice calculations with almost quark flavors and the thermal contributions from photons, neutrinos, leptons, electroweak particles, and scalar Higgs bosons, various thermodynamic quantities, at vanishing net-baryon densities, such as pressure, energy density, bulk viscosity, relaxation time, and temperature have been calculated up to the TeV-scale, i.e. covering hadron, QGP and electroweak (EW) phases in the early Universe. This remarkable progress motivated the present study to determine the possible influence of the bulk viscosity in the early Universe and to understand how this would vary from epoch to epoch. We have taken into consideration first- (Eckart) and second-order (Israel-Stewart) theories for the relativistic cosmic fluid and integrated viscous equations of state in Friedmann equations. Nonlinear nonhomogeneous differential equations are obtained as analytical solutions. For Israel-Stewart, the differential equations are very sophisticated to be solved. They are outlined here as road-maps for future studies. For Eckart theory, the only possible solution is the functionality, $H(a(t))$, where $H(t)$ is the Hubble parameter and $a(t)$ is the scale factor, but none of them so far could to be directly expressed in terms of either proper or cosmic time $t$. For Eckart-type viscous background, especially at finite cosmological constant, non-singular $H(t)$ and $a(t)$ are obtained, where $H(t)$ diverges for QCD/EW and asymptotic EoS. For non-viscous background, the dependence of $H(a(t))$ is monotonic. The same conclusion can be drawn for an ideal EoS. We also conclude that the rate of decreasing $H(a(t))$ with increasing $a(t)$ varies from epoch to epoch, at vanishing and finite cosmological constant. These results obviously help in improving our understanding of the nucleosynthesis and the cosmological large-scale structure.

gr-qc↗

arXiv2020

A minimal Length Uncertainty Approach to Cosmological Constant Problem

Based on quantum mechanical framework for the minimal length uncertainty, we demonstrate that the generalized uncertainty principle (GUP) parameter could be best constrained by recent gravitational waves observations on one hand. On other hand this suggests modified dispersion relations (MDRs) enabling an estimation for the difference between the group velocity of gravitons and that of photons. Utilizing features of the UV/IR correspondence and the obvious similarities between GUP (including non-gravitating and gravitating impacts on Heisenberg uncertainty principle) and the discrepancy between the theoretical and the observed cosmological constant (apparently manifesting gravitational influences on the vacuum energy density), we suggest a possible solution for the cosmological constant problem.

gr-qc↗

arXiv2020

Consequences of Minimal Length Discretization on Line Element, Metric Tensor and Geodesic Equation

When minimal length uncertainty emerging from generalized uncertainty principle (GUP) is thoughtfully implemented, it is of great interest to consider its impacts on {\it "gravitational} Einstein field equations (gEFE) and to try to find out whether consequential modifications in metric manifesting properties of quantum geometry due to quantum gravity. GUP takes into account the gravitational impacts on the noncommutation relations of length (distance) and momentum operators or time and energy operators, etc. On the other hand, gEFE relates {\it classical geometry or general relativity gravity} to the energy-momentum tensors, i.e. proposing quantum equations of state. Despite the technical difficulties, we confront GUP to the metric tensor so that the line element and the geodesic equation in flat and curved space are accordingly modified. The latter apparently encompasses acceleration, jerk, and snap (jounce) of a particle in the {\it "quasi-quantized"} gravitational field. Finite higher-orders of acceleration apparently manifest phenomena such as accelerating expansion and transitions between different radii of curvature, etc.

gr-qc↗

arXiv2020

A Possible Solution of the Cosmological Constant Problem based on Minimal Length Uncertainty and GW170817 and PLANCK Observations

We propose the generalized uncertainty principle (GUP) with an additional term of quadratic momentum motivated by string theory and black hole physics as a quantum mechanical framework for the minimal length uncertainty at the Planck scale. We demonstrate that the GUP parameter, $β_0$, could be best constrained by the the gravitational waves observations; GW170817 event. Also, we suggest another proposal based on the modified dispersion relations (MDRs) in order to calculate the difference between the group velocity of gravitons and that of photons. We conclude that the upper bound reads $β_0 \simeq 10^{60}$. Utilizing features of the UV/IR correspondence and the obvious similarities between GUP (including non-gravitating and gravitating impacts on Heisenberg uncertainty principle) and the discrepancy between the theoretical and the observed cosmological constant $Λ$ (apparently manifesting gravitational influences on the vacuum energy density), known as {\it catastrophe of non-gravitating vacuum}, we suggest a possible solution for this long-standing physical problem, $Λ\simeq 10^{-47}~$GeV$^4/\hbar^3 c^3$.

physics.gen-ph↗

arXiv2020

An almost-entirely precise empirical estimation for various chemical potentials

The transverse momentum spectra of the well-identified produced particles, $π^+$, $π^-$, $K^+$, $K^-$, $p$, $\bar{p}$, $K_s^0$, $Λ$, $\barΛ$, $Ξ^-$, and $Ξ^+$ are analyzed in a statistical approach. From the partition function of grand-canonical ensemble, we propose a generic expression for the dependence of the generic chemical potential $μ$ on the rapidity $y$. Then, by fitting this expression to the experimental results on the most central $p_{\perp}$ and $d^2 N/2 πp_{\bot} dp_{\bot} dy$, at energies ranging from $7.7$ to $200~$GeV, we have introduced a generic expression for the rapidity dependence of $μ$, at different energies, namely $μ=a+b y^2$, where $a$ and $b$ is constants. We find that the resulting energy dependence $\sqrt{s_{\mathtt{NN}}}=c[(μ-a)/b]^{d/2}$ agrees well with the statistical thermal models. We also present precise estimations of various types of chemical potentials, $μ_B$, $μ_S$, and $μ_Q$, the baryon, the strangeness, and the charge chemical potential, respectively.

hep-ph↗

arXiv2020

Hadronization correspondence of Hawking-Unruh radiation from rotating and electrically charged black holes

The proposed correspondence between the Hawking-Unruh radiation mechanism in rotating, electrically-charged and electrically-charged-rotating black holes and the hadronization in high-energy physics is assumed. This allows us to determine the well-profound freezeout parameters of the heavy-ion collisions. Furthermore, black holes thermodynamics is found analogical to that of the high-energy collisions. We also introduce a relation expressing the dependence of the angular momentum and the angular velocity deduced from rotating black holes on the chemical potential. The novel phase diagram for rotating, electrically-charged and electrically-charged-rotating black holes are found in an excellent agreement with the phase diagrams drawn for electrically-charged black holes and also with the ones mapped out from the statistical thermal models and the high-energy experiments. Moreover, our estimations for the freezeout conditions $\langle E\rangle/\langle N\rangle$ and $s/T^3$ are in excellent good agreement with the ones determined from the hadronization process, especially at $μ\leq 0.3$ GeV.

hep-ph↗

arXiv2020

Deconfinement and freezeout boundaries in equilibrium thermal models

In different approaches, the temperature-baryon density plane of QCD matter is studied for deconfinement and chemical freezeout boundaries. Results from various heavy-ion experiments are compared with the recent lattice simulations, the effective QCD-like Polyakov linear-sigma model, and the equilibrium thermal models. Along the entire freezeout boundary, there is an excellent agreement between the thermal model calculations and the experiments. Also, the thermal model calculations agree well with the estimations deduced from the Polyakov linear-sigma model (PLSM). At low baryonic density or high energies, both deconfinement and chemical freezeout boundaries are likely coincident and therefore the agreement with the lattice simulations becomes excellent as well, while at large baryonic density, the two boundaries become distinguishable forming a phase where hadrons and quark-gluon plasma likely coexist.

hep-ph↗

arXiv2020

Extensive/nonextensive statistics for $p_T$ distributions of various charged particles produced in p+p and A+A collisions in a wide range of energies

We present a systematic study for the statistical fits of the transverse momentum distributions of charged pions, Kaons and protons produced at energies ranging between 7.7 and 2670 GeV to the extensive Boltzmann-Gibbs (BG) and the nonextensive statistics (Tsallis as a special type and the generic axiomatic nonextensive approach). We also present a comprehensive review on various experimental parametrizations proposed to fit the transverse momentum distributions of these produced particles. The inconsistency that the BG approach is to be utilized in characterizing the chemical freezeout, while the Tsallis approach in determining the kinetic freezeout is elaborated. The resulting energy dependence of the different fit parameters largely varies with the particle species and the degree of (non)extensivity. This manifests that the Tsallis nonextensive approach seems to work well for p+p rather than for A+A collisions. Drawing a complete picture of the utilization of Tsallis statistics in modeling the transverse momentum distributions of several charged particle produced at a wide range of energies and accordingly either disprove or though confirm the relevant works are main advantages of this review. We propose analytical expressions for the dependence of the fit parameters obtained on the size of the colliding system, the energy, as well as the types of the statistical approach applied. We conclude that the statistical dependence of the various fit parameters, especially between Boltzmann and Tsallis approaches could be understood that the statistical analysis ad hoc is biased to the corresponding degree of extensivity (Boltzmann) or nonextensivity (Tsallis). Alternatively, the empirical parameterizations, the other models, and the generic (non)extensive approach seem to relax this biasness.

hep-ph↗

arXiv2019

Transverse momentum spectra of strange hadrons within extensive and nonextensive statistics

Using generic (non)extensive statistics, in which the underlying system autonomously manifests its extensive and nonextensive statistical nature, we extract various fit parameters from the CMS experiment and compare these to the corresponding results obtained from Tsallis and Boltzmann statistics. The present study is designed to indicate the possible variations between the three types of statistical approaches and characterizes their dependence on collision energy, multiplicity, and size of the system of interest. We analyze the transverse momentum spectra $p_T$ of the strange hadrons \Kslxi produced in Pb+Pb collisions, at 2.76 TeV, in p+Pb collisions, at 5.02 TeV, and in $p+p$ collisions, at 7 TeV. From the comparison of the resulting fit parameters; temperature $T$, volume $V$, and nonextensvie parameter $d$, with calculations based on Tsallis and Boltzmann statistics, remarkable differences between the three types of statistics are determined besides a strong dependence on size and type of the colliding system. We conclude that the produced particles with large masses and large strange quantum numbers likely freeze out earlier than the ones with smaller masses and less strange quantum numbers. This conclusion seems not depending on the type of the particle or the collision but apparently manifesting transitions from chemical (larger temperature) to the kinetic freezeouts (lower temperature). For the first university (equivalent) class c=1, the decrease in the second one, $d$, with increasing energy and collision centrality highlights that the system departs from nonextensivity (non-equilibrium) and apparently approaches extensivity (equilibrium) indicating that the Boltzmann statistics becomes the proper statistical approach in describing that system. Last but not least, we present analytical expressions for the energy dependence of the various fit parameters.

hep-ph↗

arXiv2019

Multiplicity per rapidity in Carruthers and hadron resonance gas approaches

The multiplicity per rapidity of the well-identified particles $π^{-}$, $π^{+}$, $k^{-}$, $k^{+}$, $\bar{p}$, $p$, and $p-\bar{p}$ measured in different high-energy experiments, at energies ranging from $6.3$ to $5500~$GeV, are successfully compared with the Cosmic Ray Monte Carlo (CRMC) event generator. For these rapidity distributions, we introduce a theoretical approach based on fluctuations and correlations (Carruthers) and another one based on statistical thermal assumptions (hadron resonance gas model). Both approaches are fitted to the two sets of results deduced from experiments and simulations. We found that the Carruthers approach reproduces well the full range of multiplicity per rapidity for all produced particles, at the various energies, while the HRG approach fairly describes the results within a narrower rapidity-range. While the Carruthers approach seems to match well with the Gaussian normal distribution, ingredients such as flow and interactions should be first incorporated in the HRG approach.

hep-ph↗

arXiv2019

SU(3) Polyakov Linear-Sigma Model With Finite Isospin Asymmetry: QCD Phase Diagram

The SU($3$) Polyakov linear-sigma model (PLSM) in mean-field approximation is utilized in analyzing the chiral condensates $σ_u$, $σ_d$, $σ_s$ and the deconfinement order parameters $ϕ$, $\barϕ$, at finite isospin asymmetry. The bulk thermodynamics including pressure density, interaction measure, susceptibility, and second-order correlations with baryon, strange and electric charge quantum numbers are studied in thermal and dense medium. The PLSM results are confronted to the available lattice QCD calculations. The excellent agreement obtained strengthens the reliability of fixing the PLSM parameters and therefore supports further predictions even beyond the scope of the lattice QCD numerical applicability. From the QCD phase structure at finite isospin chemical potential ($μ_I$), a novel expression for the explicit symmetry breaking term $h_3$ is introduced, we find that the pseudo-critical temperatures decrease with the increase in $μ_I$. We conclude that the QCD phase structure in ($T_χ$-$μ_I$) plane seems to extend the one in ($T_χ$-$μ_B$) plane.

hep-ph↗

arXiv2019

Polyakov linear-sigma model in mean-field approximation and optimized perturbation theory

We compare results from the Polyakov linear-sigma model (PLSM) in optimized perturbation theory (OPT) with the mean-field approximation (MFA). At finite temperatures and chemical potentials, the chiral condensates and the decofinement order parameters, the thermodynamic pressure, the pseudo-critical temperatures, the subtracted condensates, the second- and high-order moments of various conserved charges (cumulants) obtained in MFA are compared with OPT and also confronted to available lattice QCD simulations. We conclude that when moving from lower- to higher-order moments of various quantum charges, OPT becomes more closer to QCD.

hep-ph↗