Charged kaon identification with the RICH in τ decays

Kaon production in the decay of the tau lepton has been studied with the data collected by the DELPHI detector at LEP. Charged kaons were identified by the DELPHI barrel ring imaging Cherenkov detector with two techniques, “ring” and “veto” identification. Both inclusive and exclusive branching ratios of charged kaon production in single-prong tau decay were measured. The kaon identification techniques were extended to the case of multi-prong tau decays, which provides the possibility to measure the kaon production in multi-prong tau decay and the tau neutrino mass.