physics at HERA could show up in the production of exotic high mass events
with unusual signatures or also by deviations of the observed SM cross
sections from the predictions. Our grous works on both aspects since several
years. All analyses explore the region of highest Q2 .
H1 has observed a few exotic events which are difficult to explain within the SM. There signature is:
Event with a high Pt muon and missing transverse momentum
the standard model the only known process which leads to such a signature
is W-production where the W decays into lepton and neutrino.
Indeed a fraction of the observed events are well compatible with this expected process. There is however an excess in cross section and some of the
events have kinematic properties which are very rare for W-production. The consistency with the SM prediction of the H1 observations is below 1%.
ZEUS has no excess in the electron and muon channels. They have however recently observed an exceess in the tau-channel.
A possible interpretation of theses events -apart from a still possible
statistical fluctuation - could be top-production via flavour changing
neutral currents e.g. u--> t transitions. The analysis of this