Studies of identified hadrons in qq events at LEP I, in $W^{+}W^{-}$ and $\overline{q}q$ events at LEP II and search for stable and long-lived heavy charged particles

The use of RICH detectors allows the identification of charged pions, kaons and protons, covering the full momentum range 0.7<or=p<or=E/sub beam//c. The pi /sup +or-/, K/sup +or-/ and p(p) normalised production rates, their differential cross-sections, multiplicities and the xi /sub p/ distributions are measured for three event samples, i.e. Z/sup 0/ to qq, Z/sup 0/ to bb and Z/sup 0/ to uu, dd, ss, selected from ~1,400,000 Z/sup 0/ decays collected by DELPHI in 1994. This study has been extended to high-energy qq events at LEPII. New heavy particles from 2 GeV/c/sup 2/ to the kinematic limit at LEPII have been searched using the RICH detectors. (21 refs).