We consider an approximation procedure to evaluate the finite-temperature
one-loop fermionic density in the presence of a chiral background field which
systematically incorporates effects from inhomogeneities in the chiral field
through a derivative expansion. We apply the method to the case of a simple
low-energy effective chiral model which is commonly used in the study of the
chiral phase transition, the linear sigma-model coupled to quarks. The
modifications in the effective potential and their consequences for the bubble
nucleation process are discussed.Comment: 11 pages, 5 figures. v2: appendix and references added, published
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