QCD Predictions for Meson Electromagnetic Form Factors at High Momenta: Testing Factorization in Exclusive Processes

TL;DR

This paper presents the first lattice QCD calculations of pion and kaon electromagnetic form factors at high momentum transfer, validating QCD factorization and providing benchmarks for upcoming experiments.

Contribution

It provides ab-initio lattice QCD results for meson form factors at high Q^2 and tests the universality of meson distribution amplitudes within the factorization framework.

Findings

Good agreement with JLab data at low Q^2

Provides QCD benchmarks for future experiments at high Q^2

Supports universality of meson distribution amplitudes

Abstract

We report the first lattice QCD computation of pion and kaon electromagnetic form factors, $F_M(Q^2)$, at large momentum transfer up to 10 and 28 $\mathrm{GeV}^2$, respectively. Utilizing physical masses and two fine lattices, we achieve good agreement with JLab experimental results at $Q^2 \lesssim 4~\mathrm{GeV}^2$. For $Q^2 \gtrsim 4~\mathrm{GeV}^2$, our results provide $\textit{ab-initio}$ QCD benchmarks for the forthcoming experiments at JLab 12 GeV and future electron-ion colliders. We also test the QCD collinear factorization framework utilizing our high-$Q^2$ form factors at next-to-next-to-leading order in perturbation theory, which relates the form factors to the leading Fock-state meson distribution amplitudes. Comparisons with independent lattice QCD calculations using the same framework demonstrate, within estimated uncertainties, the universality of these nonperturbative quantities.