Search for neutral and charged Higgs bosons in e+e- collisions at √s=161 GeV and 172 GeV

A search for neutral and charged Higgs bosons has been performed in the data collected by the DELPHI detector at centre-of-mass energies of 161 GeV and 172 GeV. The analysis assumes either the pair-production of charged Higgs bosons, H+/-, or the production of the lightest neutral Higgs boson, h, with either a Z or a neutral pseudoscalar Higgs boson, A. All final state topologies expected from the decay of h and A into hadrons or a pair of tau leptons, and from the decay of H+/- into a pair of quarks or a tau nu(tau) pair have been considered. Lower limits at the 95% confidence level have been obtained on the Higgs boson masses. The limits are 66.2 GeV/c(2) for h in the Standard Model, 59.5 GeV/c(2) for h and 51.0 GeV/c(2) for A in the minimal supersymmetric extension of the Standard Model with sensible assumptions on the model parameters and, using the 161 GeV data only, 51.5 GeV/c(2) for H+/- in the general two-doublet scheme for H+/- branching fractions into hadrons below 0.8.