Fragmentation function for charmed quarks from neutrino data

Abstract Data on μ + μ − and μ − e + events from the CERN-Dortmund-Heidelberg-Saclay and Columbia-BNL neutrino experiments, respectively, are employed to determine the fragmentation function for charmed quarks. It is found that the data are all well described by a flat fragmentation function D ( z ) (where z is the energy fraction taken by the charmed meson), in agreement with the expectation from bremsstrahlung-type models. The data definitely exclude a behaviour ∼exp(−3 z ), typical of uncharmed hadrons, suggested by a previous phenomenological analysis. They also discriminate against the possibility that the fragmentation function is concentrated at large z , as predicted by fireball-type models.