  We compute the finite temperature induced fermion number for fermions coupled
to a static nonlinear sigma model background in (2+1) dimensions, in the
derivative expansion limit. While the zero temperature induced fermion number
is well known to be topological (it is the winding number of the background),
at finite temperature there is a temperature dependent correction that is
nontopological -- this finite T correction is sensitive to the detailed shape
of the background. At low temperature we resum the derivative expansion to all
orders, and we consider explicit forms of the background as a CP^1 instanton or
as a baby skyrmion.

High Energy Physics - Theory