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

TL;DR

This paper reports on the search for muon neutrino to tau neutrino oscillations using the CHORUS detector at CERN, analyzing several years of data without observing any tau neutrino candidates, thus setting a new limit on the oscillation probability.

Contribution

It provides new experimental limits on $ u_ au$ appearance in muon neutrino beams, based on analysis of extensive data collected by the CHORUS detector.

Findings

No $ u_ au$ candidates found in the data.

Sets a 90% confidence level limit of $P( u_ ext{mu} o u_ au) < 6.0 imes 10^{-4}$.

Analyzed over 75,000 neutrino interactions from 1994-1996.

Abstract

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 $\nu_{\tau}$ charged current interactions followed by the $\tau$ 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 $\nu_{\tau}$ candidate has been found. This result leads to a 90% C.L. limit $P(\numtonut)< 6.0\cdot 10^{-4}$ on the mixing probability.