Local multiboson factorization of the quark determinant

TL;DR

This paper explores a multiboson domain-decomposed factorization method for the fermion determinant in lattice QCD, enabling independent updates of multiple space-time regions and improving signal-to-noise ratios in correlation functions.

Contribution

It introduces a multilevel Monte Carlo approach using multiboson factorization for lattice QCD, enhancing computational efficiency for hadronic physics calculations.

Findings

Numerical evidence of effective two-level integration for pseudoscalar propagators.

Improved signal-to-noise ratio in vector propagator calculations.

Potential applications to muon g-2 and heavy meson decay form factors.

Abstract

We discuss the recently proposed multiboson domain-decomposed factorization of the gauge-field dependence of the fermion determinant in lattice QCD. In particular, we focus on the case of a lattice divided in an arbitrary number of thick time slices. As a consequence, multiple space-time regions can be updated independently. This allows to address the exponential degradation of the signal-to-noise ration of correlation functions with multilevel Monte Carlo sampling. We show numerical evidence of the effectiveness of a two-level integration for pseudoscalar propagators with momentum and for vector propagators, in a two active regions setup. These results are relevant to lattice computation of the hadronic contributions to the anomalous magnetic moment of the muon and to heavy meson decay form factors.