Moments of Meson Distribution Amplitudes from Lattice QCD
Thomas Rae (University of Southampton)

Meson distribution amplitudes (DAs) are non-perturbative hadronic parameters that are required in many QCD calculations. DAs describe the momentum-fraction distribution of the quarks and anti-quarks within the meson. Experimental input for the DAs is limited, as they always appear as part of a convolution and cannot be cleanly isolated in collider experiments. Therefore theoretical calculations are required. We use lattice QCD to calculate the lowest moments of the DAs for the pseudoscalar mesons (\(\pi\) and \(K\)) and the longitudinally polarised vector mesons (\(\rho\), \(K^*\) and \(\phi\)). Operators are renormalised non-perturbatively and extrapolations to the physical point are made, guided by leading order chiral perturbation theory. The main results presented are for two lattices with different volumes but a common lattice spacing. Preliminary results for a finer lattice will be discussed. This provides a clear description from first principles which can be combined with experimental results for phenomenology.