DERIVATIVE EXPANSION OF THE EFFECTIVE ACTION IN YANG-MILLS THEORY

The effective action model for mesons relies on the one-loop effective action in quantum chromodynamics in the presence of a constant backgr ound chromoelectric field in a fixed direction in group space. We exte nd this effective action so as to include those terms quadratic in the first derivate of the field, for both a chromoelectric and chromomagn etic background field. An instability arises in the chromoelectric cas e.