RI / MOM renormalization window and Goldstone pole contamination

We perform a comparative study of the ratio of lattice (Wilson fermion) renormalization constants Z_P/Z_S, obtained non-perturbatively from the RI/MOM renormalization conditions and from Ward Identities of on- and off-shell Green's functions. The off-shell Ward Identity used in this work relies on correlation functions with non-degenerate quark masses. We find that, due to discretization effects, there is a 10-15% discrepancy between the two Ward Identity determinations at current bare couplings (beta values). The RI/MOM result is in the same range and has a similar systematic error of 10-15%. Thus, contrary to a previous claim, the contamination of the RI/MOM result from the presence of a Goldstone pole at scales of about 2 GeV is subdominant, compared to finite cutoff effects.

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LATEX, 12 pages final version to appear on Phys. Lett. B

fermion: lattice field theory
gauge field theory: SU(3)
renormalization
Ward identity
approximation: quenching
Goldstone particle
correlation function: analytic properties
numerical calculations: Monte Carlo

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