Domain decomposition improvement of quark propagator estimation

TL;DR

This paper introduces a domain decomposition method to improve the estimation of quark propagators in lattice QCD, offering a direct approach that enhances open propagator calculations and shows modest benefits for closed propagators.

Contribution

The authors develop a domain decomposition technique that improves quark propagator estimation, directly addressing the Dirac operator and extending maximal variance reduction methods.

Findings

Improved open propagator estimates for the Chirally Improved operator.

Preliminary results show enhanced static-light meson spectrum calculations.

Modest noise reduction observed in disconnected correlators for closed propagators.

Abstract

Applying domain decomposition to the lattice Dirac operator and the associated quark propagator, we arrive at expressions which, with the proper insertion of random sources therein, can provide improvement to the estimation of the propagator. Schemes are presented for both open and closed (or loop) propagators. In the end, our technique for improving open contributions is similar to the ``maximal variance reduction'' approach of Michael and Peisa, but contains the advantage, especially for improved actions, of dealing directly with the Dirac operator. Using these improved open propagators for the Chirally Improved operator, we present preliminary results for the static-light meson spectrum. The improvement of closed propagators is modest: on some configurations there are signs of significant noise reduction of disconnected correlators; on others, the improvement amounts to a smoothening of the same correlators.