Fragmentation functions of pions and kaons in the nonlocal chiral quark model

Abstract

Abstract. We investigate the unpolarized pion and kaon fragmentation functions using the nonlocal chiral-quark model. In this model the interactions between the quarks and pseudoscalar mesons is manifested nonlocally. In addition, the explicit flavor SU(3) symmetry breaking effect is taken into account in terms of the current quark masses. The results of our model are evaluated to higher Q 2 value Q 2 = 4 GeV 2 by the DGLAP evolution. Then we compare them with the empirical parametrizations. We find that our results are in relatively good agreement with the empirical parametrizations and the other theoretical estimations.

Overview of Gluon Helicity Measurements at STAR

“…The hard parton scattering process f 1 f 2 → f 3 f 4 is modelled by the hardscattering cross section σ (k i ) and the parton-level longitudinal double-spin asymmetry âLL (k i ), which are both calculable in perturbative QCD and are dependent on the parton momenta k i [14,15]. Finally, for the production of a hadron h from a scattered parton f 3 , there is an additional contribution from the fragmentation function D h f 3 (z), where z is the fraction of the momentum of f 3 carried by h [16].…”