Spontaneously broken quark helicity symmetry
  We discuss the origin of chiral symmetry breaking in the light-cone representation of QCD. In particular, we show how quark helicity symmetry is spontaneously broken in SU(N) gauge theory with massless quarks if that theory has a condensate of fermion lightcone zero modes. The symmetry breaking appears as induced interactions in an effective lightcone Hamiltonian equation based on a trivial vacuum. The induced interaction is crucial for generating a splitting between pseudoscalar and vector meson masses, which we illustrate with spectrum calculations in some 1+1-dimensional reduced models of gauge theory. 
S. Dalley, G. McCartor