Computing numerically the functional derivative of an effective action
arXiv:hep-ph/9511231
Abstract
The functional derivative of the effective action with respect to an external field is part of the equation of motion of this field if one-loop effects induced by quantum fluctuations or thermal fluctuations are included when minimizing the action of this field. Examples occur in all field theories displaying classical solutions or - as in the Nambu-Jona-Lasinio model - self consistent field configurations. We describe here a numerical method for computing such functional derivatives; we use a fermion field with Yukawa interaction to an external field as an example which is sufficiently simple and sufficiently general. We compare the computed functional derivative to analytical estimates.
23 pages, 5 figures in a separate uu file, macros: epsfig.sty