Pion and kaon parton distribution functions from basis light front quantization and QCD evolution

Abstract

We investigate the parton distribution functions (PDFs) of the pion and kaon from the eigenstates of a light-front effective Hamiltonian in the constituent quark-antiquark representation suitable for low-momentum scale applications. By taking these scales as the only free parameters, the valence quark distribution functions of the pion, after QCD evolving, are consistent with the E615 experiment at Fermilab. In addition, the ratio of the up quark distribution in the kaon to that in the pion also agrees with the NA3 experimental result at CERN.

Proton structure from a light-front Hamiltonian

“…In this picture, the sea quark and gluon components of the constituent quarks are revealed at the higher scale through QCD. While applying the DGLAP equations numerically [113], we impose the condition that the running coupling α s ðμ 2 Þ saturates in the infrared at a cutoff value of max α s ¼ 1 [114,115], consistent with our fit value discussed above. Allowing μ 2 0 to be different for different order of pertubative evolution, we determine them by requiring the result after evolutions to produce the total first moments of the valence quark unpolarized PDFs from the NNPDF3.0 global fit [38].…”

Tomography of light mesons in the light-cone quark model

“…We explicitly evolve our initial PDFs from the LCQM model for the pion to the relevant experimental scales μ 2 ¼ 16 GeV 2 using the Higher Order Perturbative Parton Evolution toolkit to numerically solve the NNLO DGLAP equations [150]. While applying the DGLAP equations numerically, we impose the condition that the running coupling α s ðμ 2 Þ saturates in the infrared at a cutoff value of max α s ¼ 1 [151][152][153][154].…”

Constraining gluon density of pions at large x by pion-induced J/ψ production

“…On the theoretical side, the interest in the meson structure has considerably increased in recent years. Numerous new calculations, based on the chiral-quark model [22][23][24], Nambu-Jona-Lasinio model [25], light-front Hamiltonian [26,27], holographic QCD [28,29], maximum entropy method [30], and continuum functional approach using Dyson-Schwinger equations (DSE) [31][32][33][34][35][36], became available. A major breakthrough in lattice QCD [37] led several groups to perform a direct calculation of the pion valence x distribution [38][39][40][41][42].…”