Emergence of pion parton distributions

Supposing only that there is an effective charge which defines an evolution scheme for parton distribution functions (DFs) that is all-orders exact, strict lower and upper bounds on all Mellin moments of the valence-quark DFs of pionlike systems are derived. Exploiting contemporary results from numerical simulations of lattice-regularized quantum chromodynamics (QCD) that are consistent with these bounds, parameter-free predictions for pion valence, glue, and sea DFs are obtained. The form of the valence-quark DF at large values of the light-front momentum fraction is consistent with predictions derived using the QCD-prescribed behavior of the pion wave function.National Natural Science Foundation of China (NSFC) 12135007 11805097Helmholtz-Zentrum Dresden-Rossendorf High Potential ProgrammeSpanish GovernmentEuropean Commission PID2019-107844GB-C22Junta de Andalucia P18-FR-5057 UHU-1264517 UHU EPIT-2021STRONG-2020 "The strong interaction at the frontier of knowledge: fundamental research and applications" from the European Union's Horizon 2020 research and innovation programme 82409