Induced Bwedge F term and photon mass generation in 3+1 dimensions

Analysing a 3+1 dimensional model with four-Fermi interactions, we show that topological $\BF$ terms (both abelian and non-abelian) can be induced radiatively by massive fermions at the one-loop level. It is further pointed out that a mechanism of photon (or non-abelian gauge field) mass generation distinct from the usual Higgs mechanism, through the $\BF$ term, is also implemented in the long-distance effective action of this model, provided a gap equation is satisfied.