Search for Charged Higgs Bosons at LEP in General Two Higgs Doublet Models

Abstract

A search for pair-produced charged Higgs bosons was performed in the data collected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 209 GeV. Five different final states, tau+ nu_tau tau- anti-nu_tau, c sbar cbar s, c sbar tau- anti-nu_tau, W* A W* A and W* A tau- anti-nu_tau were considered, accounting for the major expected decays in type I and type II Two Higgs Doublet Models. No significant excess of data compared to the expected Standard Model processes was observed. The existence of a charged Higgs boson with mass lower than 76.7 GeV/c^2 (type I) or 74.4 GeV/c^2 (type II) is excluded at the 95% confidence level, for a wide range of the model parameters. Model independent cross-section limits have also been calculated.