3-point functions from twisted mass lattice QCD at small quark masses

TL;DR

This paper demonstrates that Wilson twisted mass fermions enable the calculation of matrix elements between pion states at small quark masses, showing good scaling behavior and allowing reliable continuum extrapolations in lattice QCD.

Contribution

It introduces a method to compute 3-point functions at small pion masses using twisted mass lattice QCD, extending the accessible mass range for such calculations.

Findings

Scaling behavior consistent with O(a^2) in quenched approximation

Reliable continuum extrapolations at small pion masses

First lattice QCD results at pseudo scalar masses around 270 MeV

Abstract

We show at the example of the matrix element between pion states of a twist-2, non-singlet operator that Wilson twisted mass fermions allow to compute this phenomenologically relevant quantitiy at small pseudo scalar masses of O(270 MeV). In the quenched approximation, we investigate the scaling behaviour of this observable that is derived from a 3-point function by applying two definitions of the critical mass and find a scaling compatible with the expected O(a^2) behaviour in both cases. A combined continuum extrapolations allows to obtain reliable results at small pion masses, which previously could not be explored by lattice QCD simulations.