Multi-lepton production and a search for doubly-charged Higgs at HERA

Searching a Doubly Charged Higgs Boson at Hera

The production of a single exotic Higgs particle is studied at Hera. Within the present limits on the Yukawa couplings this doubly charged particle, suggested by the left-right symmetric models, can be observed at Hera up to values of its mass of about 150 GeV. PACS numbers:

Limits on doubly charged Higgs bosons and lepton-flavor violation.

Search for doubly charged Higgs bosons with lepton-flavor-violating decays involving tau leptons.

We search for pair production of doubly charged Higgs particles (H+/- +/-) followed by decays into electron-tau (etau) and muon-tau (mutau) pairs using data (350 pb(-1) collected from [over]pp collisions at sqrt[s]=1.96 TeV by the CDF II experiment. We search separately for cases where three or four final-state leptons are detected, and combine results for exclusive decays to left-handed etau (...

Single production of doubly charged Higgs bosons at hadron colliders

We reconsider the single production of the doubly charged Higgs bosons ∆ R and ∆ ++ L at the LHC and TEVATRON in the framework of the left-right symmetric model and the Higgs triplet model. We show that in the left-right symmetric model the production of ∆ R by Drell-Yan process via WR exchange may give the dominant contribution. The same channel for the production of ∆ L in the Higgs triplet m...

Multi-lepton production at high transverse momentum at HERA

A search for events containing two or more high-transverse-momentum isolated leptons has been performed in ep collisions with the ZEUS detector at HERA using the full collected data sample, corresponding to an integrated luminosity of 480 pb. The number of observed events has been compared with the prediction from the Standard Model, searching for possible deviations, especially for multilepton...