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arXiv · 2206.04084

Pion distribution amplitude at the physical point using the leading-twist expansion of the quasi-distribution-amplitude matrix element

Xiang Gao·Andrew D. Hanlon·Nikhil Karthik·Swagato Mukherjee·Peter Petreczky·Philipp Scior·Sergey Syritsyn·Yong Zhao
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Abstract

We present a lattice QCD determination of the distribution amplitude (DA) of the pion and the first few Mellin moments from an analysis of the quasi-DA matrix element within the leading-twist framework. We perform our study on a HISQ ensemble with $a=0.076$ fm lattice spacing with the Wilson-Clover valence quark mass tuned to the physical point. We analyze the ratios of pion quasi-DA 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. We find a robust result for the first non-vanishing Mellin moment $\langle x^2 \rangle = 0.287(6)(6)$ at a factorization scale $μ=2$ GeV. We also present different Ansätze-based reconstructions of the $x$-dependent DA, from which we determine the perturbative leading-twist expectations for the pion electromagnetic and gravitational form-factors at large momentum transfers.

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Xiang Gao, Andrew D. Hanlon, Nikhil Karthik, Swagato Mukherjee, Peter Petreczky, Philipp Scior, Sergey Syritsyn, Yong Zhao. 2022-10-19. Pion distribution amplitude at the physical point using the leading-twist expansion of the quasi-distribution-amplitude matrix element. https://doi.org/10.1103/physrevd.106.074505

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