Impacts of B-factory measurements on determination of fragmentation functions from electron-positron annihilation data

摘要

Fragmentation functions are determined for the pion and kaon by globalanalyses of charged-hadron production data in electron-positron annihilation.Accurate measurements were reported by the Belle and BaBar collaborations forthe fragmentation functions at the center-of-mass energies of 10.52 GeV and10.54 GeV, respectively, at the KEK and SLAC B factories, whereas otheravailable $e^+e^-$ measurements were mostly done at higher energies, mainly atthe $Z$ mass of 91.2 GeV. There is a possibility that gluon fragmentationfunctions, as well as quark fragmentation functions, are accurately determinedby scaling violation. We report our global analysis of the fragmentationfunctions especially to show impacts of the B-factory measurements on thefragmentation function determination. Our results indicate that thefragmentation functions are determined more accurately not only by the scalingviolation but also by high-statistical nature of the Belle and BaBar data.However, there are some tensions between the Belle and BaBar data in comparisonwith previous measurements. We also explain how the flavor dependence of quarkfragmentation functions and the gluon function are separated by usingmeasurements at different $Q^2$ values. In particular, the electric and weakchanges are different depending on the quark type, so that a light-quark flavorseparation also became possible in principle due to the precise data at both$\sqrt{s}\simeq 10.5$ GeV and 91.2 GeV.