Nonequilibrium Quantum-Field Dynamics and Off-Shell Transport for $Ï^4$-theory in 2+1 dimensions
arXiv:nucl-th/0401046 · doi:10.1016/j.nuclphysa.2004.07.010
Abstract
We solve the Kadanoff-Baym equations for nonequilibrium initial configurations of the $Ï^4$-theory in 2+1 dimensions and compare to explicit solutions of generalized transport equations for the same theory. The latter transport equations are derived from the Kadanoff-Baym equation in a first order gradient expansion in phase space and explicitly retain the off-shell dynamics as inherent in the time-dependent spectral functions. The solutions of these equations compare very well with the exact solutions of the full Kadanoff-Baym equations with respect to the occupation numbers of the individual modes, the spectral evolution as well as the chemical equilibration process. Furthermore, the proper equilibrium off-shell distribution is reached for large times contrary to the quasiparticle Boltzmann limit. We additionally present a direct comparison of the solution of the generalized transport equations in the Kadanoff-Baym and Botermans-Malfliet form; both solutions are found to agree very well with each other.
43 pages, LaTex, including 15 postscript figures, submitted to Nucl. Phys. A