1994/05/23 by Fred Cooper, Salman Habib, Yuval Kluger +3 · 2 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Electrodynamics and Casimir Effect #Quantum, superfluid, helium dynamics #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.50.2848
published as Phys.Rev.D50:2848-2869,1994 · 43 pages, LA-UR-94-783 (PRD, in press), uuencoded PostScript
arxiv created 1994/05/23 · openalex publication_date 1994/08/15 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
An effective action technique for the time evolution of a closed system consisting of one or more mean fields interacting with their quantum fluctuations is presented. By marrying large-N expansion methods to the Schwinger-Keldysh closed time path formulation of the quantum effective action, causality of the resulting equations of motion is ensured and a systematic, energy-conserving and gauge-invariant expansion about the quasiclassical mean field(s) in powers of 1/N developed. The general method is exposed in two specific examples, O(N) symmetric scalar \ensuremathλ\mathrm\ensuremathΦ4 theory and quantum electrodynamics (QED) with N fermion fields. The \ensuremathλ\mathrm\ensuremathΦ4 case is well suited to the numerical study of the real time dynamics of phase transitions characterized by a scalar order parameter. In QED the technique may be used to study the quantum nonequilibrium effects of pair creation in strong electric fields and the scattering and transport processes in a relativistic e+e^\mathrm\ensuremath- plasma. A simple renormalization scheme that makes practical the numerical solution of the equations of motion of these and other field theories is described.