Second moment of the pion's distribution amplitude

TL;DR

This paper reports preliminary lattice QCD calculations of the second moment of the pion's distribution amplitude, providing nonperturbative renormalization and chiral extrapolation results.

Contribution

First lattice QCD determination of the second moment of the pion's distribution amplitude with nonperturbative renormalization.

Findings

<xi^2>=0.281(28) at 5 GeV^2

a_2=0.236(82) for the Gegenbauer moment

Results obtained with two flavors of dynamical fermions

Abstract

We present preliminary results from the QCDSF/UKQCD collaborations for the second moment of the pion's distribution amplitude with two flavours of dynamical fermions. We use nonperturbatively determined renormalisation coefficients to convert our results to the MSbar scheme at 5 GeV^2. Employing a linear chiral extrapolation from our large pion masses >550 MeV, we find <xi^2>=0.281(28), leading to a value of a_2=0.236(82) for the second Gegenbauer moment.