arXiv subjects

Faqir C. Khanna

Publications and source records attributed to Faqir C. Khanna.

30 records · Page 2Linked to original sources

arXiv2020

Casimir effect and Stefan-Boltzmann law at finite temperature in a Friedmann-Robertson-Walker universe

A spatially flat Friedmann-Robertson-Walker background with a general scale factor is considered. In this space-time, the energy-momentum tensor of the scalar field with a general curvature coupling parameter is obtained. Using the Thermo Field Dynamics (TFD) formalism the Stefan-Boltzmann law and the Casimir effect at finite temperature are calculated. The Casimir effect at zero temperature is also considered. The expansion of the universe changes these effects. A discussion of these modifications is presented.

hep-th↗

arXiv2019

Casimir effect and Stefan-Boltzmann law in Yang-Mills theory at finite temperature

A non-Abelian gauge theory describes the strong interactions among particles with the commutator of generators are non-zero. An $SU(3)$ gauge theory describes the interactions that lead to nuclear forces among particles. The Lagrangian density refers to fermions with colour and flavour and the gauge field quanta implying gluons. The gauge theory is treated at finite temperature using the Thermo Field Dynamics (TFD). Using self interaction of gluons the Stefan-Boltzmann law and the Casimir effect are calculated at finite temperature. An appendix is attached to give a response of a massless quarks in gauge theory.

hep-th↗

arXiv2019

Lorentz violation and Gravitoelectromagnetism: Casimir effect and Stefan-Boltzmann law at Finite temperature

The standard model and general relativity are local Lorentz invariants. However it is possible that at Planck scale there may be a breakdown of Lorentz symmetry. Models with Lorentz violation are constructed using Standard Model Extension (SME). Here gravitational sector of the SME is considered to analyze the Lorentz violation in Gravitoelectromagnetism (GEM). Using the energy-momentum tensor, the Stefan-Boltzmann law and Casimir effect are calculated at finite temperature to ascertain the level of local Lorentz violation. Thermo Field Dynamics (TFD) formalism is used to introduce temperature effects.

hep-th↗

arXiv2018

Lorentz violation, Möller scattering and finite temperature

Lorentz and CPT symmetries may be violated in new physics that emerges at very high energy scale, i.e., at the Planck scale. The differential cross section of the Möller scattering, due to Lorentz violation at finite temperature is calculated. Lorentz-violating effects emerge from an interaction vertex due to a CPT-odd nonminimal coupling in the covariant derivative. The finite temperature effects are determined using the Thermo Field Dynamics (TFD) formalism.

hep-th↗

arXiv2018

Lorentz violation, Gravitoelectromagnetism and Bhabha Scattering at finite temperature

Gravitoelectromagnetism (GEM) is an approach for the gravitation field that is described using the formulation and terminology similar to that of electromagnetism. The Lorentz violation is considered in the formulation of GEM that is covariant in its form. In practice such a small violation of the Lorentz symmetry may be expected in a unified theory at very high energy. In this paper a non-minimal coupling term, which exhibits Lorentz violation, is added as a new term in the covariant form. The differential cross section for Bhabha scattering in the GEM framework at finite temperature is calculated that includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to calculate the total differential cross section at finite temperature. The contribution due to Lorentz violation is isolated from the total cross section. It is found to be small in magnitude.

hep-th↗

arXiv2018

Lorentz Violation, Gravitoelectromagnetic Field and Bhabha Scattering

Lorentz symmetry is a fundamental symmetry in the Standard Model (SM) and in General Relativity (GR). This symmetry holds true for all models at low energies. However at energies near the Planck scale, it is conjectured that there may be a very small violation of Lorentz symmetry. The Standard Model Extension (SME) is a quantum field theory that includes a systematic description of Lorentz symmetry violations in all sectors of particle physics and gravity. In this paper SME is considered to study the physical process of Bhabha Scattering in the Gravitoelectromagnetism (GEM) theory. GEM is an important formalism that is valid in a suitable approximation of general relativity. A new non-minimal coupling term that violates Lorentz symmetry is used in this paper. Differential cross section for gravitational Bhabha scattering is calculated. The Lorentz violation contributions to this GEM scattering cross section are small and are similar in magnitude to the case of the electromagnetic field.

hep-th↗

arXiv2017

On Fermion-Graviton Scattering at Finite Temperature

The early universe is dominated by phenomena at high temperatures. The thermal effects decrease during evolution of the universe. However there are some phenomena, such as processes inside stars and black holes, where the role of the temperature is important. Study of processes involving gravitons at finite temperature is a viable means to understand gravitational processes in the universe. Using the Thermo Field Dynamics formalism transition amplitudes involving gravitons and fermions at finite temperature are calculated. In this approach our results consist of two parts: one corresponding to the zero temperature part and the other corresponding to a temperature dependent part.

gr-qc↗

arXiv2017

Non-relativistic Casimir effect at finite temperature

The Galilean covariance, formulated in 5-dimensions space, describes the non-relativistic physics in a way similar to quantum field theory. Using a non-relativistic approach the Stefan-Boltzmann law and the Casimir effect at finite temperature for a particle with spin zero and $1/2$ are calculated. The Thermo Field Dynamics is used to calculate the temperature effect.

hep-th↗

arXiv2016

Gravitational Casimir effect at finite temperature

The energy-momentum tensor for the gravitoelectromagnetism (GEM) theory in the real-time finite temperature field theory formalism is presented. Expressions for the Casimir energy and pressure at zero and finite temperature are obtained. An analysis of the Casimir effect for the GEM field is developed.

hep-th↗

arXiv2016

Scattering of Fermions by Gravitons

The interaction between gravitons and fermions is investigated in the teleparallel gravity. The scattering of fermions and gravitons in the weak field approximation is analyzed. The transition amplitudes of M$\varnothing$ller, Compton and new gravitational scattering are calculated.

gr-qc↗

arXiv2016

Quantized gravitoelectromagnetism theory at finite temperature

The Gravitoelectromagnetism (GEM) theory is considered in a lagrangian formulation using the Weyl tensor components. A perturbative approach to calculate processes at zero temperature has been used. Here the GEM at finite temperature is analyzed using Thermo Field Dynamics, real time finite temperature quantum field theory. Transition amplitudes involving gravitons, fermions and photons are calculated for various processes. These amplitudes are likely of interest in astrophysics.

hep-th↗

arXiv2010

Entanglement discontinuity

We identify a class of two-mode squeezed states which are parametrized by an angular variable ${0\leθ<2π}$ and a squeezing parameter $r$. We show that, for a large squeezing value, these states are either (almost) maximally entangled or product states depending on the value of $θ$. This peculiar behavior of entanglement is unique for infinite dimensional Hilbert space and has consequences for the entangling power of unitary operators in such systems. Finally, we show that, at the limit ${r\to\infty}$ these states demonstrate a discontinuity attribute of entanglement.

quant-ph↗