The $\eta_c$-meson leading-twist distribution amplitude

TL;DR

This study computes the leading-twist distribution amplitude of the $$-meson using lattice QCD, employing a comprehensive approach that includes extrapolation to the physical point and comparison with other theoretical methods.

Contribution

It introduces a lattice QCD-based method to determine the $$-meson distribution amplitude at leading twist, including a detailed error analysis and comparison with alternative approaches.

Findings

Good agreement with Dyson-Schwinger equations.

Discrepancy with non-relativistic QCD results.

Successful extrapolation to physical quark masses.

Abstract

In this project, we employ the short-distance factorization to compute the distribution amplitude of the $\eta_c$-meson from Lattice QCD at leading twist. We employ a set of CLS $N_f=2$ ensembles at three lattice spacings and various quark masses to extrapolate the pseudo distribution to the physical point in the isospin limit. We solve the inverse problem modeling the distribution amplitude, and we match our results to the light-cone in the $\overline{\text{MS}}$-scheme. We include a complete error budget, and we compare to two alternative approaches: non-relativistic QCD and Dyson-Schwinger equations, finding good agreement with the latter but not with the former.