Covariant Feynman rules at finite temperature: Application to nuclear matter

Abstract

A unified treatment of relativistic many-body systems at finite temperature and density, incorporating both real- and imaginary-time formalisms, is applied to hadronic field theories of nuclear matter (quantum hadrodynamics). Covariant Feynman rules are given, which permit direct calculations in any convenient reference frame or in manifestly covariant form. The real-time rules are illustrated by the derivation of covariant expressions for the one-loop energy-momentum tensor. Next, the partition function is evaluated at one-loop order, which yields the thermodynamic potential and pressure in covariant form and verifies the virial theorem. Finally, covariant imaginary-time rules are shown to reproduce the real-time one-loop calculations.