ζ-function regularization, the multiplicative anomaly, and finite temperature quantum field theory -: art. no. 105001

We discuss the role of the multiplicative anomaly for a complex scalar field at finite temperature and density. It is argued that physical considerations must be applied to determine which of the many possible expressions for the effective action obtained by the functional integral method is correct. This is done by first studying the non-relativistic field where the thermodynamic potential is well known. The relativistic case is also considered. We emphasize that the role of the multiplicative anomaly in finite temperature quantum field theory is not to lead to new physics, but rather to preserve the equality among the various expressions for the effective action. [S0556-2821(98)11320-6].