Authors
Gao, Xiang; Hanlon, Andrew D. ; Karthik, Nikhil; Mukherjee, Swagato; Petreczky, Peter; Scior, Philipp; Syritsyn, Sergey; Zhao, Yong
Abstract
We present a lattice QCD determination of the distribution amplitude (DA) of the pion and thefirst few Mellin moments from an analysis of the quasi-DA matrix element within the leading-twistframework. We perform our study on a HISQ ensemble with a = 0.076 fm lattice spacing with theWilson-Clover valence quark mass tuned to the physical point. We analyze the ratios of pion quasiDA matrix elements at short distances using the leading-twist Mellin operator product expansion(OPE) at the next-to-leading order and the conformal OPE at the leading-logarithmic order. Wefind a robust result for the first non-vanishing Mellin moment hx2i = 0.287(6)(6) at a factorizationscale = 2 GeV. We also present different Ansatze-based reconstructions of the x-dependent DA,from which we determine the perturbative leading-twist expectations for the pion electromagneticand gravitational form-factors at large momentum transfers.