Author:

Publisher:

Published: 2001

Total Pages:

ISBN-13:

A search for charged Higgs bosons at the Large Electron and Positron Collider (LEP) at CERN is presented. Specifically the decay of the charged Higgs boson (H^+/- ) into a CP-odd Higgs boson (A^0) and a virtual W boson (W^*) has been investigated at the OPAL detector. This decay channel can be very important depending on the theoretical model. The A^0 boson decays into b-quarks while the W^* boson can decay into two quarks or into a lepton and neutrino. Since charged Higgs bosons are assumed to be pair-produced at the LEP collider, the channel has at least eight jets. A decay of one of the charged Higgs bosons into a tau-lepton and its neutrino is also possible. This channel has at least four jets. Higgs boson mass limits are obtained in the context of Two-Higgs-Doublet-Models as a function of the model-parameters, tan(beta), m(H^+/- ) and m(A^0). The results are combined with those obtained from searches in which the charged Higgs boson decays only into cs or tau-lepton + neutrino. A lower limit of m(H^+/- )>60 GeV/c^2, independent of m(A^0), is obtained at tan(beta)=100. The largest excluded charged Higgs mass is 89 GeV/c^2 for m(A^0) around 45 GeV/c^2. Furthermore, results of the charged Higgs boson search of the four LEP experiments (ALEPH, DELPHI, L3 and OPAL) are combined, excluding the decay H^+/- -> W^* A^0. A lower mass limit of m(H^+/- )>79.8 GeV/c^2 is thereby achieved.