A Nonlinear Model for Relativistic Electrons at Positive Temperature
  We study the relativistic electron-positron field at positive temperature in the Hartree-Fock-approximation. We consider both the case with and without exchange term, and investigate the existence and properties of minimizers. Our approach is non-perturbative in the sense that the relevant electron subspace is determined in a self-consistent way. The present work is an extension of previous work by Hainzl, Lewin, S\'er\'e, and Solovej where the case of zero temperature was considered. 
Christian Hainzl, Mathieu Lewin, Robert Seiringer