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Check of a new non-perturbative mechanism for elementary fermion mass generation

P. Dimopoulos, S. Capitani, G.M. De Divitiis, R. Frezzotti, M. Garofalo, B. Knippschild, B. Kostrzewa, K. Ottnad, G. Rossi, M. Schröck, C. Urbach

in 34th annual International Symposium on Lattice Field Theory

Contribution: pdf


We consider a field theoretical model where a SU(2) fermion doublet, subjected to non-Abelian
gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an irrelevant
Wilson-like term. Despite the presence of these two chiral breaking operators in the Lagrangian,
an exact symmetry acting on fermions and scalars prevents perturbative mass corrections. In
the phase where fermions are massless (Wigner phase) the Yukawa coupling can be tuned to a
critical value at which chiral transformations acting on fermions only become a symmetry of the
theory (up to cutoff effects). In the Nambu-Goldstone phase of the critical theory a fermion mass
term of dynamical origin is expected to arise in the Ward identities of the purely fermionic chiral
transformations. Such a non-perturbative mechanism of dynamical mass generation can provide a
“natural” (à la ’t Hooft) alternative to the Higgs mechanism adopted in the Standard Model. Here
we lay down the theoretical framework necessary to demonstrate the existence of this mechanism
by means of lattice simulations.