DELPHI Event r0021987e0003505

e+ e- ---> e+ e- gamma
The e+ (36.5 GeV, left) and e- (30.5 GeV, right) produce clean showers in the HPC.

In addition a shower from a neutral particle with 19.1 GeV is also seen in the HPC. It cannot be due to bremsstrahlung in the material, given that both tracks are below the beam energy. It can be interpreted as radiation from the initial or the final state electrons. This is, however, an infrequent configuration as the gamma has large energy and is emitted at large angle.