%0 Journal Article
%T Existence of a stable polarized vacuum in the Bogoliubov-Dirac-Fock approximation
%A Christian Hainzl
%A Mathieu Lewin
%A Eric Sere
%J Physics
%D 2004
%I arXiv
%R 10.1007/s00220-005-1343-4
%X According to Dirac's ideas, the vacuum consists of infinitely many virtual electrons which completely fill up the negative part of the spectrum of the free Dirac operator $D^0$. In the presence of an external field, these virtual particles react and the vacuum becomes polarized. In this paper, following Chaix and Iracane ({\it J. Phys. B}, 22, 3791--3814, 1989), we consider the Bogoliubov-Dirac-Fock model, which is derived from no-photon QED. The corresponding BDF-energy takes the polarization of the vacuum into account and is bounded from below. A BDF-stable vacuum is defined to be a minimizer of this energy. If it exists, such a minimizer is solution of a self-consistent equation. We show the existence of a unique minimizer of the BDF-energy in the presence of an external electrostatic field, by means of a fixed-point approach. This minimizer is interpreted as the polarized vacuum.
%U http://arxiv.org/abs/math-ph/0403005v3