Constraints on SUSY Seesaw from Leptogenesis and LFV

We study constraints on the fundamental parameters of supersymmetric type I seesaw models imposed by neutrino data, charged lepton flavor violation, thermal leptogenesis and perturbativity of the neutrino Yukawa couplings.Comment: 4 pages, 2 figures, to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

The SUSY seesaw model and lepton-flavor violation at a future electron-positron linear collider

We study lepton-flavor violating slepton production and decay at a future e^+e^- linear collider in context with the seesaw mechanism in mSUGRA post-LEP benchmark scenarios. The present knowledge in the neutrino sector as well as improved future measurements are taken into account. We calculate the signal cross-sections \sigma(e^{+/-}e^- -> l_{\beta}^{+/-} l_{\alpha}^- \tilde{\chi}_b^0 \tilde{\chi}_a^0); l_{\delta}=e, \mu, \tau; \alpha =|= \beta and estimate the main background processes. Furthermore, we investigate the correlations of these signals with the corresponding lepton-flavor violating rare decays l_{\alpha} -> l_{\beta} \gamma. It is shown that these correlations are relatively weakly affected by uncertainties in the neutrino data, but very sensitive to the model parameters. Hence, they are particularly suited for probing the origin of lepton-flavor violation.Comment: 31 pages, 10 figures, version published in Phys. Rev.

LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM

We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton mass splittings, occur not only in the left- but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br(${\tilde\tau}_R \to \mu \chi^0_1$)/Br(${\tilde\tau}_L \to \mu \chi^0_1$) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay $\mu^+ \to e^+ \gamma$, A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups.Comment: 43 pages, 17 figure