scholarly journals Shear viscosity of hot scalar field theory in the real-time formalism

2003 ◽  
Vol 67 (2) ◽  
Author(s):  
Enke Wang ◽  
Ulrich Heinz
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Real Time ◽  
Shear Viscosity ◽  
Scalar Field Theory ◽  
The Real ◽  
Time Formalism ◽  
Real Time Formalism

scholarly journals GAP EQUATION IN SCALAR FIELD THEORY AT FINITE TEMPERATURE

1999 ◽  
Vol 14 (04) ◽  
pp. 257-266
Author(s):  
KRISHNENDU MUKHERJEE
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Scalar Field ◽  
Imaginary Part ◽  
Finite Temperature ◽  
Thermal Mass ◽  
Scalar Field Theory ◽  
Gap Equation ◽  
The Real

We investigate the two-loop gap equation for the thermal mass of hot massless g2ϕ4 theory and find that the gap equation itself has a nonzero finite imaginary part. This implies that it is not possible to find the real thermal mass as a solution of the gap equation beyond g2 order in perturbation theory. We have solved the gap equation and obtained the real and imaginary parts of the thermal mass which are correct up to g4 order in perturbation theory.

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.

scholarly journals FINITE-TEMPERATURE AND FINITE-DENSITY QED: THE SCHWINGER-DYSON EQUATION IN THE REAL-TIME FORMALISM

1995 ◽  
Vol 10 (02) ◽  
pp. 199-232 ◽  
Author(s):  
KEI-ICHI KONDO ◽  
KAZUHIRO YOSHIDA
Keyword(s):  
Real Time ◽  
Finite Temperature ◽  
Dyson Equation ◽  
Temperature Phase ◽  
Continuous Variables ◽  
Imaginary Time ◽  
Gap Equation ◽  
The Real ◽  
Time Formalism ◽  
Real Time Formalism

We derive, based on the real-time formalism (especially thermo-field-dynamics), the Schwinger-Dyson gap equation for the fermion propagator in QED and the four-fermion model at finite temperature and density. We discuss some advantages of the real-time formalism in solving the self-consistent gap equation, in comparison with the ordinary imaginary-time formalism. Once we specify the vertex function, we can write down the SD equation with only continuous variables without performing the discrete sum over Matsubara frequencies which cannot be performed in advance without further approximation in the imaginary-time formalism. By solving the SD equation obtained in this way, we find the chiral-symmetry-restoring transition at finite temperature and present the associated phase diagram of strong-coupling QED. In solving the SD equation, we consider two approximations: instantaneous-exchange and p0-independent ones. The former has a direct correspondence in the imaginary-time formalism; the latter is a new approximation beyond the former, since it is able to incorporate new thermal effects which have been overlooked in the ordinary imaginary-time solution. However, the two approximations are shown to give qualitatively the same results on the finite-temperature phase transition.

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