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Abstract:

We analyze a class of supersymmetric models first introduced by Arkani-Hamed et al and Borzumati et al in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms in the MSSM super- and Kahler-potentials. The mechanism is closely related to the Giudice-Masiero mechanism for the MSSM $\mu$ parameter, and leads to TeV-scale right-handed neutrino and sneutrino states, that are in principle accessible to direct experimental study. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term induced by a lepton-number violating $B$-term for the sneutrino states that is naturally present. We focus upon the simplification and analysis of the flavour structure of this general class of models, finding that simple and novel origins for the light neutrino mass matrix are possible. We find that a subdominant tree-level `see-saw' contribution may lead to interesting perturbations of the leading one-loop-induced flavour structure, possibly generating the small ratio $\Delta m_{\rm solar}^2/\Delta m_{\rm atm}^2$ dynamically.

Abstract:

The production of black holes in extra-dimensional brane-world theories can lead to detectable signals via the Hawking evaporation of the black hole to brane-localized standard model modes. We calculate, as a function of partial wave number and number of toroidally compactified extra dimensions, the leading correction to the energy spectrum of such Hawking radiation (the greybody factors) for decay into spin-1/2 fermions and spin-1 gauge fields localized on the standard model brane. We derive the associated improved differential emission rates for both types of fields. We provide both simple expressions for the leading behavior of the greybody factors in the low-energy limit [Formula Presented] and numerical evaluation of our full analytic expressions for the emission rates, valid for [Formula Presented] The full analytic expressions demonstrate that both the greybody factors and emission rates are enhanced as the number of extra dimensions increases. © 2003 The American Physical Society.