Measurement of $D^{*+}$ production in charged-current neutrino interactions

During the years 1994-97, the emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy. In total about 100 000 charged-current neutrino interactions were located in the nuclear emulsion target and fully reconstructed. A high-statistics sample of neutrino interactions with a D^0 in the final state was collected. Using the decay mode D*^+ -> D ^0 \pi+ a production cross-section measurement of the D*^+ in neutrino-nucleon charged-current interactions was performed. The low Q-value of the decay was used to isolate a sample of candidate events containing a positive hadron with a small p_T with respect to the D^0 direction. A signal of 22.1 +- 5.5 D*^+ events was obtained. The D*^+ production cross-section relative to the D^0 production cross-section, \sigma(D*^+) / \sigma(D^0), was estimated to be 0.38 +- 0.09(stat) +- 0.05(syst). From this result, the fraction of D^0’s produced via the decay of a D* was deduced to be 0.63 +- 0.17. The D*^+ production cross-section relative to the \nu_\mu charged-current interaction, \sigma(D*^+) / \sigma(CC), was estimated to be [1.02 +-0.25(stat) +- 0.15(syst)]%.