Abstract:

Doubly-charged Higgs bosons appear in theories beyond the Standard Model, in particular, in left-right symmetric models, in Higgs triplet models and in Little-Higgs models. The models predict dominant decay modes to like-charge lepton pairs. An attractive extension of the standard model is the left-right symmetric model of weak interactions. These models require in the Higgs sector a bidoublet and two left-right symmetric triplets . It was shown that introducing of L-R Higgs triplets provides an opportunity to understand smallness of neutrino masses. This work presents a search for the pair production of doubly-charged Higgs Bosons in the process which is performed with the D0 Run II Detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive di-muon data collected at an energy of TeV, corresponding to an integrated luminosity of about 113 pb-1 and were recorded by the D0 experiment between August 2002 and June 2003. In the absence of a signal, 95% confidence level mass limits of and are set for left-handed and right-handed doubly-charged Higgs boson, assuming 100% branching into muons, hypercharge |Y| = 2, and Yukawa coupling . This is the first search for doubly-charged Higgs bosons at hadron colliders. It significantly extends the previous mass limit of 100.5 GeV/c2 for a left-handed doubly-charged Higgs boson measured in the muon final states by the OPAL collaboration. Studies of a more technical character which were important for understanding of the detector performance, such as the measured Z boson mass resolution, time dependence of reconstruction efficiencies and BR x cross section are to be presented.