6 research outputs found
Two-Dimensional Instantons with Bosonization and Physics of Adjoint
We evaluate partition functions in topologically nontrivial (instanton)
gauge sectors in the bosonized version of the Schwinger model and in a gauged
WZNW model corresponding to with adjoint fermions. We show that the
bosonized model is equivalent to the fermion model only if a particular form of
the WZNW action with gauge-invariant integrand is chosen. For the exact
correspondence, it is necessary to integrate over the ways the gauge group
is embedded into the full group for the bosonized
matter field. For even , one should also take into account the contributions
of both disconnected components in . In that case, for small fermion masses where coincides with the number of
fermion zero modes in a particular instanton background. The Taylor expansion
of in mass involves only even powers of as it should. The
physics of adjoint is discussed. We argue that, for odd , the
discrete chiral symmetry present in the action is broken
spontaneously down to and the fermion condensate is formed. The system undergoes a first order phase transition at
so that the condensate is zero at an arbitrary small temperature. It
is not yet quite clear what happens for even .Comment: 36 pages, LaTeX. References adde