Quark condensate in a magnetic field

Abstract

We study the dependence of quark condensate $\Sigma$ on an external magnetic field. For weak fields, it rises linearly with the field. Pion mass and residue are also shifted so that the Gell-Mann - Oakes - Renner relation is satisfied. In the strong field region, $\Sigma (H)\propto (eH{)}^{3/2}$.

Comments: 13 pages LaTeX, 5 postscript files for figures