DELPHI Event r0023438e0000581

e+ e- ---> Tau+ Tau-
The Tau pair is cleanly identified by a 1 vs 3 topology.

The Tau- decays into a Mu- (42.0 GeV), identified by the barrel Muon chambers and 4.7 GeV in the barrel Hadron calorimeter.

The Tau+ decays into 3 very collimated particles, Pi- (19.3 GeV), Pi+ (8.3 GeV), Pi+ (1.4 GeV), all three being minimum ionizing in the HPC and the two energetic ones depositing energy in the HAB. The 3-particle system has 29.0 GeV energy and 1.01 GeV mass, hence compatible with a Tau. They are accompanied by a 3 GeV energy deposition in the HPC, probably originating from a Pi0. The three tracks are beautifully separated in the VD, IDjet, IDtrigger and TPC.

The interest of this event resides in the fact that the candidate muon is so energetic.