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

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  GeV^{2}, respectively. Utilizing physical masses and two fine lattices, we achieve good agreement with JLab experimental results at Q^{2}≲4  GeV^{2}. For Q^{2}≳4  GeV^{2}, our results provide 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.