Sphaleron rate from a modified Backus-Gilbert inversion method
Claudio Bonanno, Francesco D’Angelo, Massimo D’Elia, Lorenzo Maio, Manuel Naviglio
Abstract
We compute the sphaleron rate in quenched quantum chromodynamics (QCD) for a temperature $T\ensuremath{\simeq}1.24\text{ }\text{ }{T}_{c}$ from the inversion of the Euclidean lattice time correlator of the topological charge density. We explore and compare two different strategies: one follows a new approach proposed in this study and consists in extracting the rate from finite lattice spacing correlators, and then in taking the continuum limit at fixed smoothing radius followed by a zero-smoothing extrapolation; the other follows the traditional approach of extracting the rate after performing such double extrapolation directly on the correlator. In both cases the rate is obtained from a recently proposed modification of the standard Backus--Gilbert procedure. The two strategies lead to compatible estimates within errors, which are then compared to previous results in the literature at the same or similar temperatures; the new strategy permits to obtain improved results, in terms of statistical and systematic uncertainties.