Measurement of fragmentation properties of charmed particle production in charged-current neutrino interactions

Abstract

During the years 1994–1997, the emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS. In total about 100 000 charged-current neutrino interactions were located in the nuclear emulsion target and fully reconstructed. From this sample of events which was based on the data acquired by new automatic scanning systems, 1048 D 0 events were selected by a pattern recognition program. They were confirmed as neutral-particle decays through visual inspection. Fragmentation properties of deep-inelastic charm production were measured using these events. Distributions of the D 0 momentum, Feynman x ( x F ), z and tan θ out , the transverse angle out of the leptonic plane defined by the muon and the neutrino, are presented. The mean value of z was measured to be 〈 z 〉 = 0.63 ± 0.03 ( stat ) ± 0.01 ( syst ) . From fits to the z distribution, values for the Peterson parameter ε P = 0.108 ± 0.017 ( stat ) ± 0.013 ( syst ) and the Collins–Spiller parameter ε CS = 0.21 −0.04 +0.05 ( stat ) ± 0.04 ( syst ) are found. For the average value of x F we find 〈 x F 〉 = 0.38 ± 0.04 ( stat ) ± 0.03 ( syst ) and for the forward–backward asymmetry A = 0.79 ± 0.14 ( stat ) ± 0.05 ( syst ) . The distribution of tan θ out was measured with an average value 〈 tan θ out 〉 = 0.030 ± 0.002 .