Finite temperature induced fermion number

Abstract

The induced fractional fermion number at zero temperature is topological (in the sense that it is only sensitive to global asymptotic properties of the background field), and is a sharp observable (in the sense that it has vanishing rms fluctuations). In contrast, at finite temperature, it is shown to be generically nontopological, and not a sharp observable.

Comments: 6 pp, 2 figs; based on talks at Workshop on Lattice Hadron Physics (Cairns, July 2001), Workshop on Light-Cone: Particles and Strings (Trento, September 2001), and Workshop on Quantum Field Theory in External Conditions (Leipzig, September 2001)