Magnetic monopoles and fermion number violation in chiral matter
  We show that the presence of a magnetic monopole in position space gives rise
to a violation of the fermion number conservation in chiral matter. Using the
chiral kinetic theory, we derive a model-independent expression of such a
violation in nonequilibrium many-body systems of chiral fermions. In local
thermal equilibrium at finite temperature and chemical potential, in
particular, this violation is proportional to the chemical potential with a
topologically quantized coefficient. These consequences are due to the
interplay between the Dirac monopole in position space and the Berry monopole
in momentum space. Our mechanism can be applied to study the roles of magnetic
monopoles in the nonequilibrium evolution of the early Universe.
