Search for charged Higgs bosons in e+e− collisions at s = 181–184 GeV

Data collected at centre-of-mass energies of 181–184 GeV by ALEPH at LEP, corresponding to an integrated luminosity of 56.9 pb−1, are analysed in a search for pair-produced charged Higgs bosons H±. Three analyses are employed to select the τ+νττ−ν̄τ, cs̄τ−ν̄τ/c̄sτ+ντ and cs̄sc̄ final states. No evidence for a signal is found. Mass limits are set as a function of the branching fraction B(H+→τ+ντ). Under the assumption that the decay modes considered cover the totality of the possible final states, charged Higgs bosons with masses below 59 GeV/c2 are excluded at 95% C.L. independently of B(H+→τ+ντ).