Recent Results From CHORUS Charm Analysis

Abstract

The CHORUS experiment was designed to search for $ν_μ\to ν_τ$ oscillation by detecting the decay topology of the $τ$ in charged current (CC) $ν_τ$ events. The detector was exposed to the Wide Band Neutrino Beam of the CERN SPS during the years 1994-1997. About $10^{6} ν_μ$ CC events were collected in the nuclear emulsion target. Up to now, about 170,000 $ν_μ$ events have been located and analysed. The speed of the automated emulsion scanning systems increases each year. With the present performance of these systems, it has become possible to perform large volume scanning. All tracks belonging to an interaction vertex can be recognized and measured precisely. This technique is not only applied to the search for neutrino oscillation but can also be used for the recognition of events where charmed particles are produced. Results obtained from the analysis of a sub-sample of the data on the production rate in $ν_μ$ CC interactions of neutral charmed mesons ($D^0$) and charmed baryons ($Λ_c$) are presented. In addition a new measurement of the branching ratio for the decays of charmed hadrons into muons is given. Also measurements of topological branching ratios of $D^0$ and $Λ_c$ are presented. Finally, a search for associated charm production is discussed.