Search for charmed hadrons in the OPERA experiment

Abstract

Abstract. The OPERA experiment was designed to study muon neutrino to tau neutrino oscillations in appearance mode, using the CERN to Gran Sasso (CNGS) high energy neutrino beam 730 km far from the source. From 2008 to 2012, CNGS neutrinos interactions were recorded in the OPERA detector, which includes target units made of lead plates alternated with emulsion films and electronic tracker planes. The on-going analysis is aimed at the detection of short-lived particle decays occurring over distances of the order of 1 mm from the neutrino interaction point. It has allowed identifying charmed hadrons together with the tau lepton decay candidates that have established ν μ → ν τ oscillations with a significance of 4.2 σ. The procedure applied in OPERA to detect short-lived particle decays and its application to the search for charmed hadrons will be discussed here in detail. IntroductionThe Oscillation Project with Emulsion tRacking Apparatus (OPERA) [1] was designed to directly observe tau-neutrino appearance in the CERN Neutrinos to Gran Sasso (CNGS) . The on-going oscillation analysis is aimed at the detection of the decays of the short-lived τ lepton originating from the oscillated ν τ CC interactions which occur over distances of the order of 1 mm from the neutrino interaction point at CNGS energies. Nuclear emulsions, instrumenting the OPERA target, are tracking detectors particularly well suited for the study of these decay processes: using the complementary information provided by electronic detectors, their event topology and kinematics can be fully reconstructed. In the following, a short description of the OPERA detector and event analysis is given, the procedure applied to detect short-lived particle decays is discussed in detail together with its application to the a e-mail: alessandra.pastore@ba.infn.it [