Controlled nonperturbative dynamics of quantum fields out-of-equilibrium

By J. Berges. 2001

195 citations recorded by the source corpus.

Abstract We compute the nonequilibrium real-time evolution of an O ( N )-symmetric scalar quantum field theory from a systematic 1/ N expansion of the 2PI effective action to next-to-leading order, which includes scattering and memory effects. In contrast to the standard 1/ N expansion of the 1PI effective action, the next-to-leading-order expansion in presence of a possible expectation value for the composite operator leads to a bounded-time evolution where the truncation error may be controlled by higher powers in 1/ N . We present a detailed comparison with the leading-order results and determine the range of validity of standard mean-field-type approximations. We investigate “quench” and “tsunami” initial conditions frequently used to mimic idealized far-from-equilibrium pion dynamics in the context of heavy-ion collisions. For spatially homogeneous initial conditions, we find three generic regimes, characterized by an early-time exponential damping, a parametrically slow (power-law) behavior at intermediate times, and a late-time exponential approach to thermal equilibrium. The different time scales are obtained from a numerical solution of the time-reversal invariant equations in 1+1 dimensions without further approximations. We discuss in detail the out-of-equilibrium behavior of the nontrivial n -point correlation functions as well as the evolution of a particle number distribution and inverse slope parameter.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b021accc9dbdaa253553802d0681905d61f035f8

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In Astronomy and Astrophysics

1. T. Prokopec
2. S. Weinstock
3. W. Buchmuller
4. D. Bodeker

In Atomic and Molecular Physics, and Optics

1. T. Prokopec
2. M. G. Schmidt
3. S. Weinstock

In Nuclear and High Energy Physics

1. T. Prokopec
2. M. G. Schmidt
3. S. Weinstock
4. W. Buchmuller
5. D. Bodeker

Citations in the corpus

• TRANSPORT EQUATIONS FOR CHIRAL FERMIONS TO ORDER ħ AND ELECTROWEAK BARYOGENESIS (2004, background): “One can in fact study the quantum dynamics of scalar fields also in the strongly coupled regime by making use of the 1/N expansion, where N denotes the number of scalar field components [22, 23, 24].”