scholarly journals REAL TIME QUANTUM FIELD THEORY AT FINITE TEMPERATURE IN AN INHOMOGENEOUS MEDIA

1996 ◽  
Vol 11 (07) ◽  
pp. 525-533
Author(s):  
TENGIZ M. BIBILASHVILI
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Density Matrix ◽  
Real Time ◽  
Chemical Potential ◽  
Initial Conditions ◽  
Quantum Field ◽  
Matrix Approach ◽  
Thermodynamical Parameters ◽  
Time Quantum

The method of the real time perturbative calculations of nonequilibrium averages is generalized to the case of varying chemical potential. Calculations are performed in the frame of Zubarev’s nonequilibrium density matrix approach. In this approach perturbations of temperature and other thermodynamical parameters are taken into account explicitly including nonlinear terms. It differs from the Schwinger-Keldysh approach through the choice of more general initial conditions for the density matrix.

Momentum space techniques for curved space–time quantum field theory

1979 ◽  
Vol 367 (1728) ◽  
pp. 123-141 ◽  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Momentum Space ◽  
Nuclear Physics ◽  
Space Time ◽  
Coordinate Space ◽  
Quantum Field ◽  
Curved Space ◽  
Time Quantum ◽  
Space Formulation

A momentum space formulation of curved space–time quantum field theory is presented. Such a formulation allows the riches of momentum space calculational techniques already existing in nuclear physics to be exploited in the application of quantum field theory to cosmology and astrophysics. It is demonstrated that one such technique can allow exact, or very accu­rate approximate, results to be obtained in cases which are intractable in coordinate space. An efficient method of numerical solution is also described.

scholarly journals The relation between quantum and classical field theory with a classical source

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200656
Author(s):  
S. A. Fulling ◽  
A. G. S. Landulfo ◽  
G. E. A. Matsas
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Classical Field Theory ◽  
Classical Field ◽  
Quantum Field ◽  
Schwarzschild Solution ◽  
Classical Source ◽  
Time Quantum ◽  
Perturbative Quantum ◽  
Classical Picture

Classical field theory is about fields and how they behave in space–time. Quantum field theory, in practice, usually seems to be about particles and how they scatter. Nevertheless, classical fields must emerge from quantum field theory in appropriate limits, and Michael Duff showed how this happens for the Schwarzschild solution in perturbative quantum gravity. In a series of papers, we and others have shown how classical radiation from an accelerated charge emerges from quantum field theory when the Unruh thermal effect is taken into account. Here, we sharpen those conclusions by showing that, even at finite times, the quantum picture is meaningful and is in close agreement with the classical picture.

scholarly journals SURPRISES IN NONPERTURBATIVE DYNAMICS IN σ-MODEL AT FINITE DENSITY

2004 ◽  
Vol 19 (18) ◽  
pp. 1341-1356 ◽  
Author(s):  
V. P. GUSYNIN ◽  
V. A. MIRANSKY ◽  
I. A. SHOVKOVY
Keyword(s):  
Elementary Particle ◽  
Field Theory ◽  
Quantum Field Theory ◽  
Particle Physics ◽  
Chemical Potential ◽  
High Density ◽  
Quantum Field ◽  
Finite Density ◽  
Elementary Particle Physics ◽  
Kaon Condensate

The linear SU (2)L× SU (2)R σ-model occupies a unique place in elementary particle physics and quantum field theory. It has been recently realized that when a chemical potential for hypercharge is added, it becomes a toy model for the description of the dynamics of the kaon condensate in high density QCD. We review recent results in nonperturbative dynamics obtained in the ungauged and gauged versions of this model.

THERMOFIELD DYNAMICS AND e+e- REACTIONS

2011 ◽  
Vol 26 (17) ◽  
pp. 2881-2897 ◽  
Author(s):  
M. CHEKERKER ◽  
M. LADREM ◽  
F. C. KHANNA ◽  
A. E. SANTANA
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Real Time ◽  
Finite Temperature ◽  
Quantum Field ◽  
Time Formalism ◽  
Hadronic State ◽  
Real Time Formalism

The thermofield dynamics, a real-time formalism for finite temperature quantum field theory, is used to calculate the rates for e+e- reactions at finite temperature. The results show the role of temperature in defining a hadronic state after the plasma has been cooled down.

REAL-TIME FORMALISM OF THERMOFIELD DYNAMICS AND MATSUBARA APPROACH IN QUANTUM STATISTICAL PHYSICS

1990 ◽  
Vol 05 (26) ◽  
pp. 2183-2188
Author(s):  
A. A. ABRIKOSOV
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Real Time ◽  
Statistical Physics ◽  
Integration Contour ◽  
Quantum Field ◽  
True Vacuum ◽  
Time Formalism ◽  
Quantum Statistical ◽  
Real Time Formalism

When studying thermodynamic properties by means of quantum field theory methods one can deform the Matsubara integration contour in the complex time plane. The deformations are restricted by Hamiltonian singularities which are due to turning on an interaction. One should construct the real-time technique in the true vacuum taking the interaction into account.

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