DELPHI Z0 PEAK EVENT

DELPHI Event r0033967e0001337


e+ e- ---> Tau+ Tau- , e- vs Pi+ K0
The isolated track (left) is reconstructed in the VD, ID, TPC as a negative particle with 12.3 GeV/c momentum. It has an HPC shower associated with 12.3 +- 0.9 GeV energy. It is a clearly identified e-.

On the three prong side, the track in the middle (blue) is measured in the VD, ID, TPC, OD as a positive with 14.0 GeV/c momentum. It appears as MIP in the HPC and has a hard shower associated in the HAB. It is thus hadronic, probably Pi+.

The other two tracks (in red) are seen on a blown-up view to join at the entry of the TPC. They have no hits in the ID nor VD. One is positive with 8.0 GeV/c, the other negative with 2.3 GeV/c. They are MIP or unseen in the HPC. They have an opening angle in Theta of 5.2 degree, which excludes a photon conversion. They correspond to the decay of a K0_S.