Phenomenology of the triplet seesaw mechanism with gauge and Yukawa mediation of SUSY breaking

Abstract

We thoroughly discuss a new supersymmetric grand unified scenario of the triplet seesaw mechanism where the exchange of heavy SU (2) W triplet states generates both neutrino masses and soft supersymmetry breaking terms. This framework, recently proposed by us in a previous work, is highly predictive since it contains only three free parameters connecting low-energy neutrino parameters, lepton and quark flavour violation, sparticle and Higgs boson spectra and electroweak symmetry breakdown. These three parameters are the triplet mass M T , the effective supersymmetry breaking scale B T and a coupling constant λ. We perform a complete analysis of the parameter space taking into account the present experimental constraints and considering different types of neutrino spectrum. A special emphasis is given to the particular features of the sparticle and Higgs spectra and to the model independent predictions obtained for the processes µ → eX, µ → e conversion in nuclei, τ → eY and τ → µY (X = γ, ee, Y = γ, ee, µµ). In the appendices, we present some technical aspects relevant for our analysis.

Beyond the standard seesaw: neutrino masses from Kähler operators and broken supersymmetry

“…14) which induce tiny splittings in the sneutrino spectrum. This property of our d = 6 operators generalizes a known effect of d = 5 type I [64,65] and type II [40,41] seesaw realizations, 3 and is potentially relevant for the phenomenon of sneutrino oscillations [64,65]. Furthermore, the presence of ∆L = 2 scalar operators induces neutrino masses at the one-loop level, as in [64][65][66][67].…”

“…In such models, which contain two Higgs superfields 1 H 1 and H 2 with opposite JHEP08(2010)133 the ∆L = 2 effective operators at the tree level, are identified with the SUSY-breaking mediators, responsible for generating sparticle masses at the quantum level through gauge and Yukawa interactions. This scenario is a variant of that proposed in [40,41] and relates neutrino and sparticle masses even more closely, since their common source is the SUSYbreaking holomorphic mass term of the heavy states. In particular, we compute the full set of MSSM SUSY-breaking terms at the heavy triplet mass scale (section 4.1) and obtain the tree-level and quantum contributions to the neutrino mass matrix (section 4.2).…”

LeptonicCPviolation

“…The same is not true for three-body decays and µ-e conversion in nuclei which, in the MSSM, are induced at one loop due to the presence of LFV soft SUSY-breaking terms like (m 2 L ) ij . Consequently, the rates for these processes will be also independent from the Majorana phases and the lightest neutrino mass (Joaquim and Rossi, 2007a). In general, this is valid in all cases with LFV in the soft SUSY-breaking sector induced by the couplings Y ∆ , as in the universal boundary condition limit (Joaquim, 2009(Joaquim, , 2010Rossi, 2002), or in the gauge-Yukawa SUSYbreaking mediation scenario (Joaquim andRossi, 2006, 2007b).…”

“…In order to eliminate the dependence on v, µ, and M ∆ , it is convenient to define ratios of BRs such as Using now the parametrization for m ν shown in Eq. (2.36), and taking into account the definitions (3.3), one can see that the quantities R ij do not depend on the Majorana phases α 1,2 and the lightest neutrino mass (Joaquim and Rossi, 2007a;Rossi, 2002). In contrast, the ratiosR τ jki may depend on all neutrino parameters (Chun et al, 2003).…”

“…In particular, a flavor suppression may occur in the τ µ and τ e channels in the CP-conserving cases. This may be have profound impact on the LFV predictions of the type II seesaw (Joaquim, 2009;Joaquim and Rossi, 2007a).…”