3,745 research outputs found
Monodromy of a Class of Logarithmic Connections on an Elliptic Curve
The logarithmic connections studied in the paper are direct images of regular
connections on line bundles over genus-2 double covers of the elliptic curve.
We give an explicit parametrization of all such connections, determine their
monodromy, differential Galois group and the underlying rank-2 vector bundle.
The latter is described in terms of elementary transforms. The question of its
(semi)-stability is addressed.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) at http://www.emis.de/journals/SIGMA
Reconciling leptogenesis with observable mu --> e gamma rates
We perform a detailed analysis of thermal leptogenesis in the framework of
seesaw models which approximately conserve lepton number. These models are
known to allow for large Yukawa couplings and a low seesaw scale in agreement
with neutrino mass constraints, and hence to lead to large lepton flavour
violating rates that can be probed experimentally. Although large Yukawa
couplings lead to (inverse) decay rates much larger than the Hubble expansion
rate, we show that the leptogenesis washout induced is generically small if the
mass splitting between the right-handed neutrinos is small enough. As a result,
large lepton flavour violating rates are compatible with successful
leptogenesis. We emphasize that this scenario does not require any particular
flavour structure. A small splitting is natural and radiatively stable in this
context because it is protected by the lepton number symmetry.Comment: One section added, a few equations and sentences rewritten,
references added, results unchange
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