Use of stochastic sources for the lattice determination of light quark physics

TL;DR

This paper evaluates the effectiveness of Z(2)xZ(2) stochastic sources in lattice QCD calculations of light quark physics, finding improved statistical accuracy for meson correlators but limited advantage for certain matrix element computations.

Contribution

It introduces and compares stochastic sources with traditional point sources in lattice QCD, highlighting their benefits and limitations for different observables.

Findings

Stochastic sources improve statistics for meson correlators.

No significant advantage of stochastic sources over traditional methods for B_K calculation.

Potential application to semileptonic form factors with twisted boundary conditions.

Abstract

In this paper we investigate the benefits of using Z(2)xZ(2) single timeslice stochastic sources for the calculation of light quark physics on the lattice. Meson 2-point correlators measured using sources stochastic in only spin and those stochastic in both spin and colour indices are compared to point source correlators on the unit gauge and on a 16^3 x 32 Domain Wall QCD ensemble. It is found that the use of stochastic sources gives a considerable improvement in statistics for the same computational cost. The neutral kaon mixing matrix element B_K is also calculated on this ensemble with stochastic sources, but we conclude that the stochastic method offers no significant advantage over the traditional gauge-fixed wall source approach which already offers an exact volume average. We also discuss the application to semileptonic form factors in conjunction with partially twisted boundary conditions.