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Neutrino masses from SUSY breaking in radiative seesaw models
Radiatively generated neutrino masses () are proportional to
supersymmetry (SUSY) breaking, as a result of the SUSY non-renormalisation
theorem. In this work, we investigate the space of SUSY radiative seesaw models
with regard to their dependence on SUSY breaking
(\require{cancel}\cancel{\text{SUSY}}). In addition to contributions from
sources of that are involved in electroweak symmetry
breaking ( contributions), and which are
manifest from
and , radiatively generated can also receive contributions from
sources that are unrelated to EWSB
( contributions). We point out that recent
literature overlooks pure- contributions
() that can arise at the same order of perturbation theory as
the leading order contribution from .
We show that there exist realistic radiative seesaw models in which the
leading order contribution to is proportional to
. To our knowledge no model with such a
feature exists in the literature. We give a complete description of the
simplest model-topologies and their leading dependence on
. We show that in one-loop realisations
operators are suppressed by at least or
. We construct a model example based on a one-loop
type-II seesaw. An interesting aspect of these models lies in the fact that the
scale of soft- effects generating the leading order
can be quite small without conflicting with lower limits on the mass of
new particles.Comment: Accepted for publication in European Physical Journal C; 23 pages +
appendices; references updated; minor revisions; extended conclusion
Slepton mass splittings and cLFV in the SUSY seesaw in the light of recent experimental results
Following recent experimental developments, in this study we re-evaluate if
the interplay of high- and low-energy lepton flavour violating observables
remains a viable probe to test the high-scale type-I supersymmetric seesaw. Our
analysis shows that fully constrained supersymmetric scenarios no longer allow
to explore this interplay, since recent LHC data precludes the possibility of
having sizeable slepton mass differences for a slepton spectrum sufficiently
light to be produced, and in association to BR(mu -> e gamma) within
experimental reach. However, relaxing the strict universality of supersymmetric
soft-breaking terms, and fully exploring heavy neutrino dynamics, still allows
to have slepton mass splittings O(few %), for slepton masses accessible at the
LHC, with associated mu -> e gamma rates within future sensitivity. For these
scenarios, we illustrate how the correlation between high- and low-energy
lepton flavour violating observables allows to probe the high-scale
supersymmetric seesaw.Comment: 19 pages, 12 eps figures. References updated; matches version
accepted by JHE
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