Measurement of D∗+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)]%

Observation of one event with the characteristics of associated charm production in neutrino charged current interactions

We report on a search for associated charm production in neutrino charged-current interactions in the CHORUS experiment, based on the visual observation of charmed-particle decays. The search differs from those carried out so far in which the production of cc has been inferred from measurements of events with two or three muons in the final state, resulting from the decay of charmed hadrons. One event with a double charm-decay topology has been found and a corresponding background of 0.04 events has been evaluated. © 2002 Elsevier Science B.V. All rights reserved.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cross-section measurement for quasielastic production of charmed baryons in nu N interactions

A study of quasielastic production of charmed baryons in charged- current interactions of neutrinos with the nuclear emulsion target of CHORUS is presented. In a sample of about 46 000 interactions located in the emulsion, candidates for decays of short-lived particles were identified by using new automatic scanning systems and later confirmed through visual inspection. Criteria based both on the topological and kinematical characteristics of quasielastic charm production allowed a clear separation between events of this type and those in which charm is produced in deep inelastic processes. A final sample containing 13 candidates consistent with quasielastic production of a charmed baryon with an estimated background of 1.7 events was obtained. At the average neutrino energy of 27 GeV the cross-section for the total quasielastic production of charmed baryons relative to the nu N charged-current cross-section was measured to be sigma (QE)/ sigma (CC)=(0.23/sub -0.06//sup +0.12 /(stat)/sub -0.03//sup + /0/sup .02/(syst))*10/sup -2/. Through an analysis of the topology at the production and decay vertices the relative cross-sections were measured separately for singly ( Lambda /sub c//sup +/, Sigma /sub c//sup +/, Sigma /sub c//sup +/*) and doubly ( Sigma /sub c//sup ++/, Sigma /sub c//sup ++/*) charged baryons. (29 refs)

Measurement of topological muonic branching ratios of charmed hadrons produced in neutrino-induced charged-current interactions.

From 1994 to 1997, the emulsion target of the CHORUS detector was exposed to the wideband 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 based on the data acquired by new automatic scanning systems; 2013 charm-decay events were selected by a pattern recognition program. They were confirmed as decays through visual inspection. Based on these events, the effective branching ratio of charmed particles into muons was determined to be (B) over bar (mu) = [7.3 +/- 0.8(stat) +/- 0.2(syst)] x 10(-2). In addition, the muonic branching ratios are presented for dominating charm-decay topologies. Normalization of the muonic decays to charged-current interactions provides sigma(mu)-(mu)+/sigma(cc) = [3.16 +/- 0.34(stat) 0.09(syst)] x 10(-3). Selecting only events with visible energy greater than 30 GeV gives a value of (B) over bar (mu) that is less affected by the charm production threshold and quasi-elastic Delta(+)(c) production. Combining this value with the current average of B 12 of vertical bar V(cd)vertical bar(LO) = 0. 236 +/- 0.016. (c) 2005 Elsevier B.V. All rights reserved