Twisted mass QCD for the pion electromagnetic form factor

TL;DR

This paper computes the pion electromagnetic form factor using quenched twisted mass QCD, demonstrating improved results and the viability of GMRES-DR matrix inverter, aligning with experimental data and other improved actions.

Contribution

It introduces the use of GMRES-DR for twisted mass QCD and applies momentum averaging to improve lattice artifacts in pion form factor calculations.

Findings

GMRES-DR is effective for twisted mass QCD matrix inversion.

Results agree with other O(a) improved actions.

Computed form factor aligns with experimental data.

Abstract

The pion form factor is computed using quenched twisted mass QCD and the GMRES-DR matrix inverter. The momentum averaging procedure of Frezzotti and Rossi is used to remove leading lattice spacing artifacts, and numerical results for the form factor show the expected improvement with respect to the standard Wilson action. Although some matrix inverters are known to fail when applied to twisted mass QCD, GMRES-DR is found to be a viable and powerful option. Results obtained for the pion form factor are consistent with the published results from other O(a) improved actions and are also consistent with the available experimental data.