Higgs boson and supersymmetric particles search in the L3 experiment

The search for the neutral Higgs boson with mass larger then 50 GeV/c2 has been performed through the processes e+e- → H0 e+e- and e+e- → H0μ+μ-. We have finalized the analysis at the c.m.s. energy corresponding to the Z boson mass and studied the data sample at LEPII where the c.m.s. energy was raised progressively to reach 161 and 172 GeV with integrated luminosities of 10.8 and 10.2 pb-1 respectively. No Higgs signal was observed. The combination of the leptonic and the hadronic channels allowed to put a lower Higgs mass limit MH > 69.5 c2 at 95% CL. At e+e- colliders, events with photons and missing energy can offer the first hint of the emergence of new physics. Different analyses have been developed to look for such anomalous events. No new signal has been found in any of the searched processes and limits have been derived on the parameters of various models. (authors)