Gauge Symmetry Breakdown due to Dyanamical versus Elementary Higgs
  We study in details on how gauge bosons can acquire mass when the chiral symmetry dynamically breaks down for massless gauge theory without scalars. Introducing dynamical scalar fields into the original gauge theory, we show that when the chiral symmetry breaks down, the theory gives gauge boson masses different from what would be obatained if an elemetary Higgs is included. We clarify the reason and propose one method how to calculate gauge boson masses in the case of dynamical gauge symmtry breakdown. We explain the method by using an example in which SU(5) massless gauge theory breaks down to SU(4) with massless fermions in appropriate representations. 
Takayuki Matsuki, Masashi Shiotani