Discrete time quantum field theory

2014 ◽  
pp. 287-305
Author(s):  
George Jaroszkiewicz
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Discrete Time ◽  
Quantum Field ◽  
Time Quantum

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.

Noncommutative quantum field theory: unitarity and discrete time

2001 ◽  
Vol 515 (3-4) ◽  
pp. 426-430 ◽  
Author(s):  
M. Chaichian ◽  
A. Demichev ◽  
P. Prešnajder ◽  
A. Tureanu
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Discrete Time ◽  
Quantum Field ◽  
Noncommutative Quantum Field Theory ◽  
Noncommutative Quantum

scholarly journals COMMENT ON FERMION PROPAGATOR IN REAL-TIME QUANTUM-FIELD THEORY AT FINITE TEMPERATURE AND DENSITY

2002 ◽  
Vol 17 (05) ◽  
pp. 303-308 ◽  
Author(s):  
A. NIÉGAWA
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Green Function ◽  
Finite Temperature ◽  
Standard Form ◽  
Quark Propagator ◽  
The Other ◽  
Quantum Field ◽  
Fermion Propagator ◽  
Time Quantum

Two forms are available for the fermion propagator at finite temperature and density. It is shown that, when one deals with a diquark-condensation-operator inserted Green function in hot and dense QCD, the standard form of the quark propagator does not work. On the other hand, another form of the quark propagator does work.

Multi-time Quantum Field Theory

2020 ◽  
pp. 41-53
Author(s):  
Matthias Lienert ◽  
Sören Petrat ◽  
Roderich Tumulka
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Field ◽  
Time Quantum

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.

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