Quark condensate in a magnetic field
Abstract We study the dependence of quark condensate Σ on an external magnetic field. For weak fields, it rises linearly: Σ(H) = Σ(0) [1 + eH ln2 (16π 2 F π 2 ) + …] . M π and F π are also shifted so that the Gell-Mann-Oakes-Renner relation is satisfied. In the strong field region, Σ(H) α (eH) 3 2 .