Disconnected contributions to hadronic structure: a new method for stochastic noise reduction

TL;DR

The paper introduces a novel, easy-to-implement stochastic noise reduction method for all-to-all propagators in lattice QCD, significantly decreasing computational costs for disconnected loop calculations.

Contribution

A new unbiased noise reduction technique that stops propagator inversion early, applicable across quark actions, and combined with hopping expansion for enhanced efficiency.

Findings

Achieved 4-12 times reduction in computational time for disconnected loops.

Combined method with hopping expansion yields up to 30-fold efficiency gains.

Method is simple to implement and maintains unbiased results.

Abstract

We present a new method for reducing the stochastic noise of all-to-all propagators based on stopping the inversion of the propagator before convergence. The method is easy to implement, unbiased and independent of the quark action. Applying this method to the calculation of disconnected loops needed for hadronic structure observables we find savings in computer time of factors of 4-12 depending on the operator inserted in the loop. When combined with a hopping parameter expansion technique we obtain combined gains of up to factors of 30 for some operators.