Global analysis of π± and K± fragmentation functions and their application to top quark decays considering new BABAR and Belle experimental data

Abstract

Recently, the Belle and BABAR collaborations published the single-inclusive electron–positron annihilation data at the center of mass energies ([Formula: see text]) of 10.52 and 10.54 GeV, respectively. These new data offer one the possibility to determine the nonperturbative initial conditions of fragmentation functions (FFs) much more accurately. Here, we extract the FFs of π± and K± particles at next-to-leading order (NLO) including these new data, which are in the regions of larger scaled-energy z and lower [Formula: see text]. However, the π± and K± FFs were calculated previously, but our new analysis shows that adding these new data, for instance, changes the (u, s) → π+ FFs in the large-z region while the s → π+ FF is also changed at low z. These new data also change the u → K+ FF at low z (z < 0.2) more than at large z, but the d → K+ FF is affected at z > 0.07. The FF of g → K+ is decreased everywhere, for example, about 25% at z = 0.01. We also apply, for the first time, the extracted FFs to make our predictions for the scaled-energy distributions of π± and K± inclusively produced in top quark decays at NLO.