Eur. Phys. J. C (2007) 52: 543-552
https://doi.org/10.1140/epjc/s10052-007-0410-8

Regular Article - Experimental Physics

Associated charm production in neutrino–nucleus interactions

¹ Cukurova University, Adana, Turkey
² NIKHEF, Amsterdam, The Netherlands
³ Physics Department of Middle East Technical University, 06531, Ankara, Turkey
⁴ Università di Bari and INFN, Bari, Italy
⁵ Humboldt Universität, Berlin, Germany
⁶ Inter-University Institute for High Energies (ULB-VUB) Brussels, Brussels, Belgium
⁷ Università di Cagliari and INFN, Cagliari, Italy
⁸ Università di Ferrara and INFN, Ferrara, Italy
⁹ Toho University, Funabashi, Japan
¹⁰ CERN, Geneva, Switzerland
¹¹ Technion, Haifa, Israel
¹² Kinki University, Higashiosaka, Japan
¹³ Gyeongsang National University, Jinju, Korea
¹⁴ Aichi University of Education, Kariya, Japan
¹⁵ Kobe University, Kobe, Japan
¹⁶ Université Catholique de Louvain, Louvain-la-Neuve, Belgium
¹⁷ Institute for Theoretical and Experimental Physics, Moscow, Russian Federation
¹⁸ Westfälische Wilhelms-Universität, Münster, Germany
¹⁹ Nagoya University, Nagoya, Japan
²⁰ Università Federico II and INFN, Naples, Italy
²¹ Osaka City University, Osaka, Japan
²² Università La Sapienza and INFN, Rome, Italy
²³ Università di Salerno and INFN, Salerno, Italy
²⁴ Utsunomiya University, Utsunomiya, Japan
²⁵ Università di Cagliari, Cagliari, Italy
²⁶ SpinX Technologies, Geneva, Switzerland
²⁷ DESY, Hamburg, Germany
²⁸ CPPM CNRS-IN2P3, Marseille, France

^* e-mail: mguler@mail.cern.ch

Received: 11 May 2007
Revised: 21 August 2007
Published online: 15 September 2007

Abstract

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 130000 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±0.05. The relative rate of the associated charm cross-section in deep inelastic ν interactions, σ(cc̄ν)/σ_NC ^DIS=(3.62^+2.95 _-2.42(stat)±0.54(syst))×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±0.06 and the upper limit on associated charm production in charged-current interactions at 90% C.L. has been found to be σ(cc̄μ^-)/σ_CC<9.69×10^-4.