Statistical quasi-particles as the normal component of a superfluid

Abstract

It is argued from the structure of many body theory Feynman graphs that the statistical average of a spontaneously broken conserved charge density decomposes naturally into two parts: (1) a “normal” part given by an ideal gas-like expression with statistical quasi-particle emergies, and (2) a “superfluid” part which vanishes when the symmetry is restored. The momentum density of a relativistic superfluid is also discussed.