Accessing the topological susceptibility via the Gribov horizon

© 2017 American Physical Society. The topological susceptibility, χ4, following the work of Witten and Veneziano, plays a key role in identifying the relative magnitude of the η′ mass, the so-called U(1)A problem. A nonzero χ4 is caused by the Veneziano ghost, the occurrence of an unphysical massless pole in the correlation function of the topological current Kμ. In this paper, we investigate the topological susceptibility, χ4, in SU(3) and SU(2) Euclidean Yang-Mills theory using an appropriate Padé approximation tool and a nonperturbative gluon propagator, within a Becchi-Rouet-Stora-Tyutin invariant framework and by taking into account Gribov copies in a general linear covariant gauge.16 pages, 6 figuresstatus: publishe