Instanton Effects in Three Flavor QCD

Michael Dine, Patrick Draper, Guido Festuccia

Published 2014-10-30Version 1

Instanton calculations in QCD are plagued by infrared divergences, and in the past there has been much discussion of what information they can meaningfully provide. Here we show that for any number of flavors and colors, including the phenomenologically relevant case, the short distance behavior of certain chirality-violating Green's functions is calculable. These correlators provide analytic access to non-perturbative phenomena in the chiral limit, and one application is to the calibration of lattice computations at small quark mass. We also revisit the related issue of the $u$ quark mass and its additive renormalization by small instantons, and discuss an alternative test of $m_u=0$ on the lattice.