Nikolai Romanenko

Single production of doubly charged Higgs bosons at hadron colliders

Abstract We reconsider the single production of the doubly charged Higgs bosons Δ R ++ and Δ 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 Δ R ++ by Drell–Yan process via W R exchange may give the dominant contribution. The same channel for the production of Δ L ++ in the Higgs triplet model is insignificant.

Signatures of Doubly Charged Higgs Bosons in e gamma Collisions

We study the discovery potential for doubly charged Higgs bosons, Delta^--, in the process e- gamma -> e+ mu- mu- for centre of mass energies appropriate to high energy e^+e^- linear colliders and the CLIC proposal. For M_Delta < sqrt{s}_{e gamma} discovery is likely for even relatively small values of the Yukawa coupling to leptons. However, even far above threshold, evidence for the Delta can be seen due to contributions from virtual intermediate Deltas although, in this case, mu- mu- final states can only be produced in sufficient numbers for discovery for relatively large values of the Yukawa couplings.

Singly charged Higgs scalars at linear collider

Abstract We consider the production of singly charged Higgs bosons in the Higgs triplet and two Higgs doublet models. We evaluate the cross sections for the pair production and the single production of charged Higgs bosons at linear collider. The decay modes of H + and the Standard Model backgrounds are considered. We analyze the possibilities to differentiate between the triplet and two Higgs doublet models.

Testing lepton number violation with the reaction

Abstract We investigate the reaction e − e − →μ ν q q as a possible place to test the lepton number violating interactions of singly charged scalars ΔL± belonging to a SU(2)L triplet. The existence of such scalars is predicted by some majoron models, as well as by the left-right symmetric extension of the Standard Model. We show that this reaction may be observed in e−e− collision well below the threshold of ΔL±. For the colliding energy s =500 GeV the mass of the singly charged Higgs triplet may be excluded up to 2 TeV and even more, depending on values of the appropriate Yukawa couplings.

Production of

We consider the reaction ee ->qqQQ as a test of lepton number non-conservation in the framework of the left-right-symmetric electroweak model. The main contributions to this process are due to Majorana neutrino exchange in t-channel and doubly charged Higgs (Delta{--}) exchange in s-channel with a pair of right-handed weak bosons (WR) as intermediate state. We show that in a linear ee collider with the collision energy of 1 TeV (1.5 TeV) the cross section of this process is 0.01 fb (1 fb), and it will, for the anticipated luminosity of 10**{35} cm**{-2}, be detectable below the WR threshold. We study the sensitivity of the reaction on the masses of the heavy neutrino, WR and Delta{--}.

q q \bar{q} \bar{q}

The process

final states in

{e}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{e}^{+}{W}_{R}^{\ensuremath{-}}{W}_{R}^{\ensuremath{-}}

e^{-} e^{-}

is studied in the framework of the left-right symmetric model. It is shown that this reaction and

collisions in the left-right symmetric model

{e}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{l}^{+}{W}_{R}^{\ensuremath{-}}{W}_{R}^{\ensuremath{-}}

Signatures of right-handed Majorana neutrinos and gauge bosons in e gamma collisions

for the arbitrary final lepton are likely to be discovered at the CLIC collider. For a relatively light doubly charged Higgs boson its mass does not have much influence on the discovery potential, while for heavier values the probability of the reaction increases.