GIANCARLO ROSSI Università di Roma Tor Vergata: Taking inspiration from lattice QCD data, we argue a finite non-perturbative mass contribution for quarks is generated as a consequence of the dynamical phenomen ofspontaneous chiral symmetry breaking, in turn triggered by the explicitly breaking of chiral symmetry induced by critical Wilson term in the action. In pure lattice QCD this mass term cannot be separated from the unavoidably associated lineary divergent contribution. However, if QCD is enlarged to a theory where also a scalar field is present, couplend to a doublet of SU(2) fermions via a Yukawa and a Wilson-like term, then in the phase where the scalar field takes a non-vanishing expectation value, a dinamically generated and "naturally" light fermion mass is conjectured to emerge at a critical value of the Yukawa coupling where the symmetry of the model is maximally enhanced. Masses dynamically generated in this way display a natural hierarchy according to which the stronger is the strongest of the interactions the fermion is subjected to the larger is its mass.

DATA: 09-05-2014