Pion and Kaon PDFs via Infrared-Safe Evolution augmented by $J/\ddot{I}ˆ$ Data Constraints

Abstract

Probing the partonic structure of the pion and the kaon provides essential insights into the non-perturbative dynamics of QCD, yet their parton distribution functions (PDFs) remain poorly constrained due to the scarcity of high-precision experimental data, especially for the gluon distributions. We present an improved determination of pion and kaon PDFs within the dynamical parton model combined with the maximum entropy method (MEM) framework. Our analysis features two key advancements: firstly, we employ an infrared-safe QCD evolution scheme, allowing the evolution to be reliably extended down to very low $Q^2$, approaching the hadronic scale; secondly, we incorporate pion- and kaon-induced $J/\ddot{I}ˆ$ hadroproduction data as crucial constraints in the global fit. We find that our approach yields a good description of the available Drell-Yan data, deep-inelastic scattering structure functions ($F_2$), and $J/\ddot{I}ˆ$ production across various energies and targets. The results provide significantly improved constraints on the gluon distributions at moderate and large $x$ in both the pion and the kaon, offering a more complete picture of their internal structure.

10 pages, 5 figures