Nontriviality of the Linear Sigma Model
  We consider techniques (based on an ultraviolet cutoff) used to prove that the pure boson ($\phi^4)_4$ field theory is trivial and apply them instead to the dynamically generated quark-level linear sigma model. This cutoff approach leads to the conclusion that the latter field theory is in fact nontrivial. 
L. R. Babukhadia and M. D. Scadron