449 research outputs found
Phenomenology of LFV at low-energies and at the LHC: strategies to probe the SUSY seesaw
We study the impact of a type-I SUSY seesaw concerning lepton flavour
violation (LFV) at low-energies and at the LHC. At the LHC, decays, in combination with other
observables, render feasible the reconstruction of the masses of the
intermediate sleptons, and hence the study of mass
differences. If interpreted as being due to the violation of lepton flavour,
high-energy observables, such as large slepton mass splittings and flavour
violating neutralino and slepton decays, are expected to be accompanied by
low-energy manifestations of LFV such as radiative and three-body lepton
decays. We discuss how to devise strategies based in the interplay of slepton
mass splittings as might be observed at the LHC and low-energy LFV observables
to derive important information on the underlying mechanism of LFV.Comment: 6 pages, 4 figures. To appear in the proceedings of the 11th
International Workshop on Tau Lepton Physics (TAU2010), Manchester, UK, 13-17
September 201
Lepton flavour violation: physics potential of a Linear Collider
We revisit the potential of a Linear Collider concerning the study of lepton
flavour violation, in view of new LHC bounds and of the (very) recent
developments in lepton physics. Working in the framework of a type I
supersymmetric seesaw, we evaluate the prospects of observing seesaw-induced
lepton flavour violating final states of the type e \mu + missing energy,
arising from e+ e- and e- e- collisions. In both cases we address the potential
background from standard model and supersymmetric charged currents. We also
explore the possibility of electron and positron beam polarisation. The
statistical significance of the signal, even in the absence of kinematical
and/or detector cuts, renders the observation of such flavour violating events
feasible over large regions of the parameter space. We further consider the
\mu-\mu- + E^T_miss final state in the e- e- beam option finding that, due to a
very suppressed background, this process turns out to be a truly clear probe of
a supersymmetric seesaw, assuming the latter to be the unique source of lepton
flavour violation.Comment: 30 pages, 48 figure
Potential of a Linear Collider for Lepton Flavour Violation studies in the SUSY seesaw
We study the potential of an e+- e- Linear Collider for charged lepton
flavour violation studies in a supersymmetric framework where neutrino masses
and mixings are explained by a type-I seesaw. Focusing on e-mu flavour
transitions, we evaluate the background from standard model and supersymmetric
charged currents to the e mu + missing E_T signal. We study the energy
dependence of both signal and background, and the effect of beam polarisation
in increasing the signal over background significance. Finally, we consider the
mu- mu- + missing E_T final state in e- e- collisions that, despite being
signal suppressed by requiring two e-mu flavour transitions, is found to be a
clear signature of charged lepton flavour violation due to a very reduced
standard model background.Comment: 8 pages, 5 figures. To appear in the proceedings of "DISCRETE 2012 -
3rd Symposium on Prospects in the Physics of Discrete Symmetries", Lisbon,
Portugal, 3-7 December 201
Production and decays of supersymmetric Higgs bosons in spontaneously broken R-parity
We study the mass spectra, production and decay properties of the lightest
supersymmetric CP-even and CP-odd Higgs bosons in models with spontaneously
broken R-parity (SBRP). We compare the resulting mass spectra with expectations
of the Minimal Supersymmetric Standard Model (MSSM), stressing that the model
obeys the upper bound on the lightest CP-even Higgs boson mass. We discuss how
the presence of the additional scalar singlet states affects the Higgs
production cross sections, both for the Bjorken process and the "associated
production". The main phenomenological novelty with respect to the MSSM comes
from the fact that the spontaneous breaking of lepton number leads to the
existence of the majoron, denoted J, which opens new decay channels for
supersymmetric Higgs bosons. We find that the invisible decays of CP-even
Higgses can be dominant, while those of the CP-odd bosons may also be sizeable.Comment: 21 pages, 8 figures; minor changes, final version for publicatio
Lepton Number Violating Radiative Decay in Models with R-parity Violation
Models with explicit R-parity violation can induce new rare radiative decay
modes of the boson into single supersymmetric particles which also violate
lepton number. We examine the rate and signature for one such decay,
, and find that such a mode will be very difficult
to observe, due its small branching fraction, even if the lepton number
violating coupling in the superpotential is comparable in strength to
electromagnetism. This parallels a similar result obtained earlier by Hewett in
the case of radiative decays.Comment: 10 pages, 2 figures(available on request), LaTex, ANL-HEP-PR-92-8
Degenerate neutrinos from a supersymmetric A_4 model
We investigate the supersymmetric A_4 model recently proposed by Babu, Ma and
Valle. The model naturally gives quasi-degenerate neutrinos that are bi-largely
mixed, in agreement with observations. Furthermore, the mixings in the quark
sector are constrained to be small, making it a complete model of the flavor
structure. Moreover, it has the interesting property that CP-violation in the
leptonic sector is maximal (unless vanishing). The model exhibit a close
relation between the slepton and lepton sectors and we derive the slepton
spectra that are compatible with neutrino data and the present bounds on
flavor-violating charged lepton decays. The prediction for the branching ratio
of the decay tau -> mu gamma has a lower limit of 10^{-9}. In addition, the
overall neutrino mass scale is constrained to be larger than 0.3 eV. Thus, the
model will be tested in the very near future.Comment: 11 pages, 6 figures. Talk given at the International Workshop on
Astroparticle and High Energy Physics (AHEP), Valencia, Spain, 14-18 Oct.
200
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