Applicability of the Wigner functional approach to evolution of quantum fields
1 P.N. Lebedev Physics Institute of the Russian Academy of Sciences, Moscow, Russia
2 Moscow Engineering Physics Institute, Moscow, Russia
3 Moscow Institute of Physics and Technology, Moscow, Russia
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Published online: 28 October 2016
Evolution of highly excited quantum field is considered in the framework of Keldysh formalism . It is demonstrated that leading order (LO) term of semiclassical approximation appears as well-known Classical Statistical Approximation (CSA). In simple case of spatially homogeneous scalar field analytical expressions for leading and next-to-leading (NLO) order are presented. It is shown that the range of applicability of CSA strongly depends on the properties of the initial state of the system.
© The Authors, published by EDP Sciences, 2016
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