Second moment of the pion's distribution amplitude
M. Göckeler, R. Horsley, D. Pleiter, P.E.L. Rakow, A. Schäfer, G. Schierholz, W. Schroers, J.M. Zanotti
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.