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Title: Neutrino masses, leptogenesis and dark matter from supersymmetry breaking
Author: West, Stephen Mathew.
ISNI:       0000 0001 2410 4048
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2005
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In this thesis, we analyse a class of supersymmetric models first introduced by ArkaniHamed et al and Borzumati et al. in which the light neutrino masses result from higherdimensional supersymmetry-breaking terms in the M88M super- and Kahler-potentials. The mechanism is closely related to the Giudice-Masiero mechanism for the M88M p, parameter, and leads to TeV-scale right-handed neutrino and sneutrino states. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term with a sub-dominant tree-level 'see-saw' contribution which may lead to interesting perturbations of the leading flavour structure, possibly generating the small ratio !:lm;olarl!:lm~tm dynamically. Using this mechanism it is also possible to construct a natural model of TeV-scale resonant leptogenesis. The model leads to large cosmological lepton asymmetries via the resonant behaviour of the one-loop self-energy contribution to the right-handed neutrino (Ni ) decay. This model addresses the primary problems of previous phenomenological studies of low-energy leptogenesis: a rational for TeV-scale right-handed neutrinos with small Yukawa couplings so that the out-of equilibrium condition for Ni decay is satisfied; the origin of the tiny, but non-zero mass splitting required between at least t,vo Ni masses; and the necessary non-trivial breaking of flavour symmetries in the right-handed neutrino sector. Following this, a weakly broken gauged 80(3) flavour symmetry is used to produce. two highly-degenerate right-handed neutrinos. It is shown that this 80(3) flavour symmetry is compatible with all fermion masses and mixings if it is supplemented with a further 8U(3) flavour symmetry. This mechanism is then embedded into the model of neutrino masses and leptogenesis described above. Lastly, we investigate why the inferred values of the cosmological baryon and dark matter densities are so strikingly similar. We consider models of dark matter possessing a particle-antiparticle asymmetry where this asymmetry determines both the baryon asymmetry and strongly effects the dark matter density, thus naturally linking Ob and 0dm. We show that sneutrinos can play the role of such dark matter.
Supervisor: Not available Sponsor: Not available
Qualification Name: University of Oxford, 2005 Qualification Level: Doctoral
EThOS ID:  DOI: Not available