No Arabic abstract
We study lepton number violation in Little Higgs model and find that the choice of putting triplet Higgs vev equal to zero so as not to have any tree level neutrino Majorana mass is not natural in the sense that such a term is generated at the one loop level. We investigate the contribution of exotic lepton number violating terms on neutrinoless double beta decay, K meson decay and on trilepton production in $ u$-N scattering.
In this note we examine the constraints imposed by muon anomalous magnetic moment ($(g-2)_mu$) and $mu^- to e^+ e^- e^-$ on lepton number violating (LNV) couplings of the triplet Higgs in Little Higgs (LH) model.
Little Higgs models with T-parity have a new source of lepton flavour violation. In this paper we consider the anomalous magnetic moment of the muon gmtwo and the lepton flavour violating decays mutoeg and tautomug in Little Higgs model with T-parity cite{Goyal:2006vq}. Our results shows that present experimental constraints of mutoeg is much more useful to constrain the new sources of flavour violation which are present in T-parity models.
We report on our study of the LFV processes mu to egamma, muto eee and mu to e conversion in the context of Little Higgs models. Specifically we examine the Littlest Higgs with T-parity (LHT) and the Simplest Little Higgs (SLH) as examples of a Product group and Simple group Little Higgs models respectively. The necessary Feynman rules for both models are obtained in the t Hooft Feynman Gauge up to order v^2/f^2 and predictions for the branching ratios and conversion rates of the LFV processes are calculated to leading order (one-loop level). Comparison with current experimental constraints show that there is some tension and, in order to be within the limits, one requires a higher breaking scale f, alignment of the heavy and light lepton sectors or almost degenerate heavy lepton masses. These constraints are more demanding in the SLH than in the LHT case.
We study Lepton Flavour Violating hadron decays of the tau lepton within the Simplest Little Higgs model. Namely we consider $tau rightarrow mu (P, V, PP)$ where $P$ and $V$ are short for a pseudoscalar and a vector meson. We find that, in the most positive scenarios, branching ratios for these processes are predicted to be, at least, four orders of magnitude smaller than present experimental bounds.
We propose a model to explain tiny masses of neutrinos with the lepton number conservation, where neither too heavy particles beyond the TeV-scale nor tiny coupling constants are required. Assignments of conserving lepton numbers to new fields result in an unbroken $Z_2$ symmetry that stabilizes the dark matter candidate (the lightest $Z_2$-odd particle). In this model, $Z_2$-odd particles play an important role to generate the mass of neutrinos. The scalar dark matter in our model can satisfy constraints on the dark matter abundance and those from direct searches. It is also shown that the strong first-order phase transition, which is required for the electroweak baryogenesis, can be realized in our model. In addition, the scalar potential can in principle contain CP-violating phases, which can also be utilized for the baryogenesis. Therefore, three problems in the standard model, namely absence of neutrino masses, the dark matter candidate, and the mechanism to generate baryon asymmetry of the Universe, may be simultaneously resolved at the TeV-scale. Phenomenology of this model is also discussed briefly.