Chiral symmetry breaking in QCD and Ginsparg-Wilson fermions

by Laurent LELLOUCH

Wednesday 22 Sept 1999, 14:00 → 14:15 Europe/Zurich

TH Auditorium (CERN)

A natural candidate for studying the non-perturbative phenomenon of spontaneous chiral symmetry breaking in QCD is the numerical simulation of QCD on a space-time lattice. This phenomenon, however, confronts the lattice approach with a twofold challenge. The first problem is that spontaneous symmetry breaking does not occur in a finite volume. We circumvent this problem by performing a finite-size scaling analysis which involves placing the system in a large enough box and confronting the dependence of the quark condensate on volume and quark mass to predictions from chiral perturbation theory, as the limit of restoration of chiral symmetry is approached (m-> 0, V finite). Such a study, however, requires controlling the chiral behaviour of the theory well, which is difficult on a discrete space-time. To address this second challenge, we turn to Ginsparg-Wilson fermions, which have recently been shown to possess a continuum-like chiral symmetry.