THERMAL GREENS-FUNCTIONS FROM QUANTUM-MECHANICAL PATH-INTEGRALS .2. INCLUSION OF FERMIONS

In a previous paper we have shown how, for bosonic fields, the generat ing functional in both relativistic quantum field theory and thermal h eld theory can be evaluated by use of a standard quantum-mechanical pa th integral. In this paper we extend this method to include fermionic fields. A particular problem is posed by Green's functions with extern al fermionic lines, where the different boundary conditions of bosons and fermions in imaginary time have to be accommodated within one path integral expression. The general procedure is worked out in the examp le of scalar and spinor self-energies in a simple model with a Yukawa coupling of a scalar to a Majorana spinor.