arXiv subjects

The CHORUS Collaboration

Publications and source records attributed to The CHORUS Collaboration.

6 recordsLinked to original sources

arXiv2008

Leading order analysis of neutrino induced dimuon events in the CHORUS experiment

We present a leading order QCD analysis of a sample of neutrino induced charged-current events with two muons in the final state originating in the lead-scintillating fibre calorimeter of the CHORUS detector. The results are based on a sample of 8910 neutrino and 430 antineutrino induced opposite-sign dimuon events collected during the exposure of the detector to the CERN Wide Band Neutrino Beam between 1995 and 1998. % with $E_{μ1},E_{μ2} > 5$ GeV and $Q^2 > 3$ GeV$^2$ collected %between 1995 and 1998. The analysis yields a value of the charm quark mass of $\mc = (1.26\pm 0.16 \pm 0.09) \GeVcc $ and a value of the ratio of the strange to non-strange sea in the nucleon of $κ= 0.33 \pm 0.05 \pm 0.05$, improving the results obtained in similar analyses by previous experiments.

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arXiv2007

Final results on nu_mu to nu_tau oscillation from the CHORUS experiment

The final oscillation analysis of the complete set of data collected by CHORUS in the years 1994--1997 is presented. Reconstruction algorithms of data extracted by electronic detectors were improved and the data recorded in the emulsion target were analysed by new automated scanning systems, allowing the use of a new method for event reconstruction in emulsion. CHORUS has applied these new techniques to the sample of 1996--1997 events for which no muons were observed in the electronic detectors. Combining the new sample with the data analysed in previous papers, the overall sensitivity of the experiment to the $ν_τ$ appearance is thus improved. In a two-neutrino mixing scheme, a 90% C.L. upper limit of $\sin^2 2θ_{μτ} < 4.4 \times 10^{-4}$ is set for large $Δm^2$, improving by a factor 1.5 the previously published CHORUS result.

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arXiv2007

Charged-Particle Multiplicities in Charged-Current Neutrino-- and Anti-Neutrino--Nucleus Interactions

The CHORUS experiment, designed to search for $ν_μ\toν_τ$ oscillations, consists of a nuclear emulsion target and electronic detectors. In this paper, results on the production of charged particles in a small sample of charged-current neutrino-- and anti-neutrino--nucleus interactions at high energy are presented. For each event, the emission angle and the ionization features of the charged particles produced in the interaction are recorded, while the standard kinematic variables are reconstructed using the electronic detectors. The average multiplicities for charged tracks, the pseudo-rapidity distributions, the dispersion in the multiplicity of charged particles and the KNO scaling are studied in different kinematical regions. A study of quasi-elastic topologies performed for the first time in nuclear emulsions is also reported. The results are presented in a form suitable for use in the validation of Monte Carlo generators of neutrino--nucleus interactions.

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arXiv2007

Associated Charm Production in Neutrino-Nucleus Interactions

In this paper a search for associated charm production both in neutral and charged current $ν$-nucleus interactions is presented. The improvement of automatic scanning systems in the {CHORUS} experiment allows an efficient search to be performed in emulsion for short-lived particles. Hence a search for rare processes, like the associated charm production, becomes possible through the observation of the double charm-decay topology with a very low background. About 130,000 $ν$ interactions located in the emulsion target have been analysed. Three events with two charm decays have been observed in the neutral-current sample with an estimated background of 0.18$\pm$0.05. The relative rate of the associated charm cross-section in deep inelastic $ν$ interactions, $σ(c\bar{c}ν)/σ_\mathrm{NC}^\mathrm{DIS}= (3.62^{+2.95}_{-2.42}({stat})\pm 0.54({syst}))\times 10^{-3}$ has been measured. One event with two charm decays has been observed in charged-current $ν_μ$ interactions with an estimated background of 0.18$\pm$0.06 and the upper limit on associated charm production in charged-current interactions at 90% C.L. has been found to be $σ(c\bar{c} μ^-)/σ_\mathrm{CC} < 9.69 \times 10^{-4}$.

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arXiv1999

New results on the numu-nutau and nue-nutau oscillation search with the CHORUS detector

The present results on the $\numtonut$ oscillation search by the CHORUS experiment at CERN are summarized. A fraction of the neutrino interactions collected in 1994-1997 has been analysed, searching for $ν_τ$ charged current interactions followed by the $τ$ lepton decay into a negative hadron, electron, or into a muon. A sample of 126,229 events with an identified muon in the final state and 19,436 events without an identified muon in the final state have been located in the emulsion target. Within the applied cuts, no $ν_τ$ candidate has been found. This result leads to a 90% C.L. limit $P(\numtonut)< 4.0\cdot 10^{-4}$ on the mixing probability. A $\nuetonut$ exclusion plot is also presented corresponding to 90% C.L. limit on the mixing probability of $P(\nuetonut)<~3.0\cdot~10^{-2}$.

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arXiv1998

New results on the numu-nutau oscillation search with the CHORUS detector

The present results on the $\numtonut$ oscillation search by the CHORUS experiment at CERN are summarised. A fraction of the neutrino interactions collected in 1994-1995-1996 by the CHORUS experiment has been analysed, searching for $ν_τ$ charged current interactions followed by the $τ$ lepton decay into a negative hadron or into a muon. A sample of 68,156 events with an identified final state muon and 7,206 events without an identified muon in the final state have been located in the emulsion target. Within the applied cuts, no $ν_τ$ candidate has been found. This result leads to a 90% C.L. limit $P(\numtonut)< 6.0\cdot 10^{-4}$ on the mixing probability.

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