We show that, if the formula for the topological charge density operator suggested by the use of fermions obeying the Ginsparg–Wilson relation is employed, it is possible to give a precise and unambiguous definition of the topological susceptibility in full QCD, ?fulltL, for finite quark masses on the lattice. The lattice expression of ?fulltL looks like the formal continuum one, in the sense that no power divergent subtractions are needed for its proper definition. As a consequence, the small mass behaviour of ?fulltL leads directly to a multiplicative renormalizable definition of the chiral condensate that does not require any power divergent subtraction.
Topological susceptibility in full QCD with Ginsparg-Wilson fermions / Giusti, L; Rossi, Gc; Testa, Massimo. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 587:(2004), pp. 157-166. [10.1016/j.physletb.2004.03.010]