arXiv subjects

K. Javidan

Publications and source records attributed to K. Javidan.

12 recordsLinked to original sources

arXiv2022

Impacts of EMC effects on the D meson modification factor in equilibrating QGP

In this article we employ the nuclear EMC effect to extract the parton distribution functions (PDFs) inside the Lead (Pb) and Gold (Au) nuclei. Extracted PDFs are utilized to obtain the transverse momentum dependent (TMD) ones, using the computing codes like Pythia 8 or MCFM-10. Through this procedure TMDPDFs for charm and bottom quarks in Au at $\sqrt{s_{NN}}=200\;GeV$, Pb at $\sqrt{s_{NN}}=2.76\;TeV$ and $\sqrt{s_{NN}}=5.02\;TeV$ are calculated. To evaluate the validity of results and investigate the influence of nuclear EMC effect, the numerated TMDs are used as input to estimate heavy quark modification factor $R_{AA}$ at transverse plane $P_T$. This observable is calculated through numerical solution of the Fokker-Planck equation. For this purpose we need to extract the drag and diffusion coefficients, using the hard thermal loop correction. It is done in the frame work of the relativistic hydrodynamics up to the third order approximation of gradient expansion. The results are compared with same solutions when the input PFDs are considered inside the unbounded protons where the nuclear effect is not included. The comparison indicates a significant improvement of computed $R_{AA}$ with available experimental data when the EMC effect is considered.

hep-ph↗

arXiv2022

Accelerated Gaussian quantum state transfer between two remote mechanical resonators

The main challenge in deterministic quantum state transfer between remote mechanical resonators is the local decoherence and the transmission losses in the communication channel. In the path of overcoming this limitation, here we employ a shortcut to adiabatic passage protocol to devise a fast and reliable evolution path between two remote mechanical modes in separate optomechanical systems. A quantum state transfer between the two nodes is conceived by engineering their coupling to an intermediate fiber optical channel. The coupling pulses are operated such that the dark eigenmode of the system is decoupled from the fiber modes and transitions to the bright modes are compensated for by counterdiabatic drives. We show that one obtains a quantum state transfer with high fidelity for various Gaussian states. The efficiency is compared to that of adiabatic passage protocol in the presence of losses and noises. Our results show that while the adiabatic passage protocol is very sensitive to the decoherence, the shortcut to adiabaticity provides a robust and fast quantum state transfer even for small values of the coupling strength. The performance of both protocols are also investigated for the case of multimode fiber through numerical and an effective single-model model which is found by the elimination of off-resonant fiber modes. Our findings may pave the way for using optomechanical systems in the realization of continuous-variable Gaussian quantum state transfer.

quant-ph↗

arXiv2021

Charm-quark pole mass from HERA Combined and LHCb charm production data

One of the most popular definition for the charm-quark mass is the charm-quark pole mass $m_c^{\rm pole}$. In this contribution, we extract the charm-quark pole mass through perturbative Quantum Chromo Dynamics (pQCD) analysis up to the next-to-next-to-leading order (NNLO) corrections from HERA Combined and LHCb charm production recent data sets. Then, we investigate for the first time the charm-quark pole mass $m_c^{\rm pole}$ pure impact, as an extra pQCD parameter on the proton Parton Distribution Functions (PDFs) at the NNLO corrections.

hep-ph↗

arXiv2020

NNLO compatibility between pQCD theory and phenomenology in determination of the $b$-quark pole and \MSbar running masses

This contribution attempts to determine the $b$-quark pole mass $M_b$ and \MSbar running mass $\overline{m}_b$ with two different approaches at the next-to-next-to-leading order (NNLO) corrections. At the first approach, we derive a relation between the $b$-quark pole mass $M_b$ and its \MSbar running mass $\overline{m}_b$ at the NNLO corrections based on the perturbative Quantum Chromo Dynamics (pQCD) predictions. At the second approach, we extract numerical values of the $b$-quark pole and \MSbar running masses based on the NNLO phenomenology of H1 and ZEUS Collaborations combined beauty vertex production experimental data. Then we discuss about the compatibility between the pQCD theory results and phenomenology approach in determination of the $b$-quark pole and \MSbar running masses at the NNLO corrections. Also, we investigate the role and influence of the $b$-quark mass as an extra degree of freedom added to the input parameters of the Standard Model Lagrangian, on the improvement of the uncertainty band of the proton parton distribution functions (PDFs) and particularly on the gluon distribution.

hep-ph↗

arXiv2020

The effect of LHC ATLAS jet production cross sections data at $ \sqrt{s} = 7$ TeV on the proton PDFs up to N3LO

The effect of full $7$ sets of LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the proton parton distribution functions (PDFs) up to next-to-next-to-next-to-leading order (NNNLO or N3LO) corrections is investigated for the first time. Phenomenologically, the proton central PDFs in this perturbative Quantum Chromo Dynamics (pQCD) analysis are defined based on the full seven data sets from HERA I and II combined. It is shown that, the LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the HERA I and II combined data reduces the error band of proton PDFs. Particularly, the uncertainties of the gluon $xg(x,Q^2)$ and charm $xc(x,Q^2)$ distributions decrease dramatically. Adding the LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the central proton PDFs improves the quality of the fit up to $\sim 1.53$ \%, $\sim 2.72$ \% and $\sim 2.80$ \% corresponding to next-to-leading order (NLO), next-to-next-to leading order (N2LO) and N3LO, respectively.

hep-ph↗

arXiv2020

Non-Extensive Behaviour of the QCD Strong Coupling Constant

The compatibility of theoretically calculated values for the strong coupling constant,through the renormalization group approach with experimental data is studied. There exist considerable divergence in-between theoretical and experimental results at low energies, which can not be explained by thermal field theory and considering chemical potential. Such great deviation can be treated successfully by considering the q-generalized statistical effects through adding a q-nonextensive parameter in the fitting of theoretical results on experimental data.

hep-ph↗

arXiv2020

Effects of high intensity Lasers on the Entanglement fidelity of quantum plasmas

The dynamics of entanglement during the low energy scattering processes in bipartite systems at the presence of a laser field is studied, using the Kramers-Henneberger unitary transformation as the semi classical counterpart of the Block-Nordsieck transformation, in the quantizied field formalism. The Stationary-state Schrodinger equation for quantum scattering process is obtained for such systems. Then, by using partial wave analysis, we introduce new form of entanglement fidelity containing high intense laser field. Therefore, the effective potential of hot quantum plasmas including plasmon and quantum screening effect is used to show entanglement fidelity ratio as a function of the laser amplitude, plasmon parameter and the Debye length parameter for elastic electron-ion collisions. It is shown that the amplitude of laser beam or free electron oscillation play important roles in the evolution of entanglement of the system.

physics.plasm-ph↗

arXiv2019

Localized waves in plasmas at varying magnetic field

By considering the continuity, Navier-Stoks and Poisson's equations in a non-relativistic frame work for plasmas, we study the behavior of small amplitude ion acoustic solitary waves in plasmas under the influence of a varying magnetic field. The result is a nonlinear wave equation which complies with the KdV-Burgers (KdVB) equation, surprisingly in the absence of thermal pressure or any dissipative effects. We show that the complete set of equations, by considering the varying magnetic field, create solitary waves which radiate energy during their traveling in the medium. An interesting result is the existence of small amplitude localized shock profiles beside the solitary waves. Properties of this solitaire solution is studied by considering different values for the environmental characters.

physics.plasm-ph↗

arXiv2019

On the high temperature limit of the Casimir energy

We introduce a useful approach to find asymptotically explicit expressions for the Casimir free energy at large temperature. The resulting expressions contain the classical terms as well as the few first terms of the corresponding heat-kernel expansion, as expected. This technique works well for many familiar configurations in Euclidean as well as non-Euclidean spaces. By utilizing this approach, we provide some new numerically considerable results for the Casimir pressure in some rectangular ideal-metal cavities. For instance, we show that at sufficiently large temperature, the Casimir pressure acting on the sidewalls of a rectangular tube can be up to twice that of the two parallel planes. We also apply this technique for calculating the Casimir free energy on a 3-torus as well as a 3-sphere. We show that a nonzero mass term for both scalar and spinor fields as well on the torus as on the sphere, violates the third law of thermodynamics. We obtain some negative values for the Casimir entropy on the 3-torus as well as on the 3-sphere. We speculate that these negative Casimir entropies can be interpreted thermodynamically as an instability of the vacuum state at finite temperatures

hep-th↗

arXiv2018

Phononic Casimir corrections for Graphene resonator

By calculating a Casimir energy for the acoustic phonons of Graphene, we find some temperature-dependent corrections for the pretension of a Graphene sheet suspended on a trench. We obtain values of the order of few mN/m for these corrections in fully as well as doubly clamped Graphene on a narrow trench with one nanometer width, at room temperature. These values are considerable compared to the experimental values, and can increase the fundamental resonance frequency of the Graphene. The values of these corrections increase by increasing the temperature, and so they can be utilized for tuning the Graphene pretension.

cond-mat.mes-hall↗

arXiv2018

Perturbative approach to the self-focusing of intense X-ray laser beam propagating in thermal quantum plasma

In this theoretical study, the problem of self-focusing of an X-ray intense laser beam in the thermal quantum plasma is studied. Using a relativistic fluid model and taking into account the hydrodynamic pressure of degenerate electrons in the zero temperature limit, the nonlinear momentum equation of electrons is solved by means of a perturbative method and the nonlinear current density of the relativistic degenerate electrons is obtained. Saving only the third-order nonlinearity of the laser beam amplitude, a nonlinear equation describing the interaction of laser beam with the quantum plasma is derived. It is shown that considering the nonlinearity of system through solving nonlinear equation of degenerate electron leads to the originally different wave equation in comparison with outcomes of the approach in which the permittivity of longitudinal waves of quantum plasma is problematically extended to the relativistic case. The evolution of laser beam spot size with Gaussian profile is considered and the effect of quantum terms on the self-focusing quality is studied. It is shown that considering quantum effects leads to the decrease in the self-focusing property and the effect of Bohm tunneling potential is more dominant than the degenerate electrons pressure term.

physics.plasm-ph↗

arXiv2017

Casimir energy for acoustic phonons in graphene

We find the Casimir energy, at finite temperature, for acoustic phonons in a Graphene sheet suspended over a rectangular trench, and the corresponding Casimir forces are interpreted as correction terms to the built-in tensions of the Graphene. We show that these corrections generally break the tensional isotropy of the membrane, and can increase or decrease the membrane tension. We demonstrate that for a narrow rectangular trench with side-lengths in the order of few nanometers and few micrometers, these temperature corrections are expected to be noticeable ($\sim 10^{-4} N/m$) at the room temperature. These corrections would be even more considerable by increasing the temperature, and can be applied for adjusting the built-in tension of the Graphene. Consequently we introduce a corrected version for the fundamental resonance frequency of the Graphene resonator.

cond-mat.mes-hall↗