HIGH ENERGY THEORY / RELATIVITY / COSMOLOGY SEMINARS

Fall 2006

Friday October 27 Seminar :

Raghvendra Srikanth (Harish-Chandra Research Institute)

Title : Bilarge neutrino mixing and lepton number violation in supersymmetric models

Abstract:

Neutrino oscillation data suggest that mixing pattern in the
lepton sector is bilarge. We have tried to understand this pattern
in some specific supersymmetric models where we have considered the
possibility of lepton number violation by both even and odd number
of units. We propose an array of gauge singlet hidden sector superfields
and three right-chiral neutrino superfields. We generate neutrino
masses by proposing nonrenormalizable interactions in the leptonic sector.
The observed pattern of bilarge mixing can be naturally explained by
the simultaneous existence of the seesaw mechanism and radiatively
induced masses. Allowed ranges of parameters in the gauge singlet
sector are delineated, corresponding to each of the cases of
normal hierarchy, inverted hierarchy and degenerate neutrinos.

We have also proposed a supergravity model by having a hidden sector
superfield carrying lepton number. We suggest specific forms of
the superpotential and the Kahler potential, which can give
$\Delta L = 2$ terms in the low-energy regime but no $\Delta L = 1$
term, thereby making the lightest supersymmetric particle to be a
candidate for dark matter.

Host : Schechter