Exact Conservation Laws of the Gradient Expanded Kadanoff–Baym Equations

• DOI: 10.1006/aphy.2001.6185
• Publication Date: 2002-09-16T13:49:23Z
• Authors: J. Knoll; Yu.B. Ivanov; D.N. Voskresensky
• Keywords: Conservation law; Momentum (technical analysis)

It is shown that the Kadanoff-Baym equations at consistent first-order gradient approximation reveal exact rather than approximate conservation laws related to global symmetries of the system. The conserved currents and energy-momentum tensor coincide with corresponding Noether quantities in the local approximation. These exact conservations are valid, provided a Phi-derivable approximation is used to describe the system, and possible memory effects in the collision term are also consistently evaluated up to first-order gradients.<br/>26 pages, feynman.package for diagrams, submitted to Annals of Physics<br/>