Thermo Field Dynamics Formalism Research Articles

On Hawking entropy revisited

The teleparallel gravity, in the weak field approximation, is considered. In the Schwarzschild space–time the gravitational Stefan–Boltzmann law is calculated. Using the first law of thermodynamics, the Hawking entropy and temperature of the black hole are calculated. Thermofield dynamics formalism is used to define the temperature-dependent theory. In addition the gravitational Casimir effect and Stefan–Boltzmann law at zero and finite temperature are calculated in Schwarzschild space–time.

Negativity of the Wigner function and thermal effects of Bell-cat states

We applied the thermofield dynamics formalism to analyze how the non-classical properties of the Bell-cat states are influenced by a gradual change of temperature values, in a thermal equilibrium system. To this purpose we calculate the thermal Wigner functions for these states, whose negative volume is associated with non-classical properties, and we evaluate how these non-classical features vary with temperature. Our results indicate that these properties are almost absent for temperatures of around 2 K.

Bhabha scattering in very special relativity at finite temperature

In this paper the differential cross section for Bhabha scattering in the very special relativity (VSR) framework is calculated. The main characteristic of the VSR is to modify the gauge invariance. This leads to different types of interactions appearing in a non-local form. In addition, using the Thermo Field Dynamics formalism, thermal corrections for the differential cross section of Bhabha scattering in VSR framework are obtained.

Gravitational Möller scattering, Lorentz violation and finite temperature

A formal analogy between the gravitational and the electromagnetic fields leads to the notion of Gravitoelectromagnetism (GEM) to describe gravitation. A Lagrangian formulation for GEM is developed for scattering processes with gravitons as an intermediate state, in addition to photons for electromagnetic scattering. The differential cross section is calculated for gravitational Möller scattering based on GEM theory. This gravitational cross section is obtained for cases where the Lorentz symmetry is maintained or violated. The Lorentz violation is introduced with the non-minimal coupling term. In addition, using the Thermo Field Dynamics formalism, thermal corrections to the differential cross section are investigated. By comparing the electromagnetic and GEM versions, of Möller scattering, it is shown that the gravitational effect may be measured at an appropriate energy scale.

Spin-1/2 Particles in Phase Space: Casimir Effect and Stefan-Boltzmann Law at Finite Temperature

The Dirac field, spin 1/2 particles, is investigated in phase space. The Dirac propagator is defined. The Thermo Field Dynamics (TFD) formalism is used to introduce finite temperature. The energy-momentum tensor is calculated at finite temperature. The Stefan-Boltzmann law is established, and the Casimir effect is calculated for the Dirac field in phase space at zero and finite temperature. A comparative analysis with these results in standard quantum mechanics space is realized.

On Regular Black Holes at Finite Temperature

The Thermo Field Dynamics (TFD) formalism is used to investigate the regular black holes at finite temperature. Using the Teleparalelism Equivalent to General Relativity (TEGR), the gravitational Stefan-Boltzmann law and the gravitational Casimir effect at zero and finite temperature are calculated. In addition, the first law of thermodynamics is considered. Then, the gravitational entropy and the temperature of the event horizon of a class of regular black holes are determined.

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 spacetime, 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.

Non-Abelian Gravitoelectromagnetism and Applications at Finite Temperature

Studies about a formal analogy between the gravitational and the electromagnetic fields lead to the notion of Gravitoelectromagnetism (GEM) to describe gravitation. In fact, the GEM equations correspond to the weak-field approximation of the gravitation field. Here, a non-abelian extension of the GEM theory is considered. Using the Thermo Field Dynamics (TFD) formalism to introduce temperature effects, some interesting physical phenomena are investigated. The non-abelian GEM Stefan-Boltzmann law and the Casimir effect at zero and finite temperatures for this non-abelian field are calculated.

Thermal representations in group field theory: squeezed vacua and quantum gravity condensates

We apply the formalism of thermofield dynamics to group field theory quantum gravity and construct thermal representations associated with generalised equilibrium Gibbs states using Bogoliubov transformations. The newly constructed class of thermal vacua are entangled, two-mode squeezed, thermofield double states. The corresponding finite temperature representations are inequivalent to the standard zero temperature one based on a degenerate vacuum. An interesting class of states, coherent thermal states, are defined and understood as thermal quantum gravity condensates.

On Gravitational Casimir Effect and Stefan-Boltzmann Law at Finite Temperature

Gravitons are described by the propagator in teleparallel gravity in nearly flat space-time. Finite temperature is introduced by using Thermofield Dynamics formalism. The gravitational Casimir effect and Stefan-Boltzmann law are calculated as a function of temperature. Then an equation of state for gravitons is determined.

Thermal corrections for gravitational Möller scattering

A Lagrangian formulation of Gravitoelectromagnetism (GEM) theory is considered. GEM is a gravitational theory that emerges from a formal analogy between electromagnetism and gravity. Using this, the differential cross-section of the gravitational Möller scattering at finite temperature is calculated. The temperature effects are introduced using the Thermo Field Dynamics (TFD) formalism.

On Lorentz violation in e− + e+ → μ− + μ+ scattering at finite temperature

Small violation of Lorentz and CPT symmetries may emerge in models unifying gravity with other forces of nature. An extension of the standard model with all possible terms that violate Lorentz and CPT symmetries are included. Here a CPT-even non-minimal coupling term is added to the covariant derivative. This leads to a new interaction term that breaks the Lorentz symmetry. Our main objective is to calculate the cross section for the e−+e+→μ−+μ+ scattering in order to investigate any violation of Lorentz and/or CPT symmetry at finite temperature. Thermo Field Dynamics formalism is used to consider finite temperature effects.

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 the 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. The Thermo Field Dynamics (TFD) formalism is used to introduce temperature effects.

Gravitoelectromagnetism, Cherenkov radiation at finite temperature

Gravitoelectromagnetism (GEM) is a gravitational theory similar to electromagnetism. The GEM Lagrangian formalism is used to consider a study of the Cherenkov radiation. This allows us to consider the interaction between gravitons and particles that are fermions. The Thermo Field Dynamics (TFD) formalism is used to introduce the temperature effects. The production rate for Cherenkov radiation at finite temperature is calculated.

Stefan-Boltzmann Law and Casimir Effect for the Scalar Field in Phase Space at Finite Temperature

We use the scalar field constructed in phase space to analyze the analogous Stefan-Boltzmann law and Casimir effect, both of them at finite temperature. The temperature is introduced by Thermo Field Dynamics (TFD) formalism and the quantities are analyzed once projected in the space of coordinates. We show that using the framework of phase space it is possible to introduce a thermal energy which is related to temperature as it vanishes when the temperature tends to zero. In fact given such a correlation the formalism of TFD is equivalent when project is in momenta space when compared to coordinates space.

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.

Lorentz Violation, Möller Scattering, and Finite Temperature

Lorentz and CPT symmetries may be violated in new physics that emerges at very high energy scale, that is, 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.

Casimir effect for the Higgs field at finite temperature

In early 1970, it was postulated that there exists a zero spin quantum field, called Higgs field, that is present in all universe. The potential energy of the Higgs field is transferred to particles. Hence they acquire mass. These ideas were essential in fulfilling the basic need for a particle, called Higgs, with mass. These particles are called Higgs particles with spin zero with its mass to be [Formula: see text][Formula: see text]125 GeV. This raises the question as to its physical effects. If these particles are present, will they exhibit a Casimir effect and also obey the Stefan–Boltzmann Law? Assuming the dynamics of this field, will these effects change with temperature. The present calculation uses thermo field dynamics formalism to calculate temperature effects.

Lorentz violation in Bhabha scattering at finite temperature

Corrections to the Bhabha scattering cross section, due to Lorentz violation, at finite temperature are calculated. The vertex interaction between fermions and photons is modified by introducing the Lorentz violation, for the Standard Model extension, from $CPT$ odd nonminimal coupling. The finite temperature corrections are calculated using the thermo field dynamics formalism. The Lorentz violation corrections are presented for zero to high temperatures.

Parity-Violating in e − e + Scattering at Finite Temperature

Parity violation implies that physics laws are not invariant under spatial coordinate reversal. Electron-positron scattering is a process that displays parity violation. Using the Thermo Field Dynamics formalism this scattering at finite temperature is analyzed. The transition amplitude is calculated as a function of temperature. The parity violation at very high temperatures tend to go to zero.