2,547,574 research outputs found
Lepton Flavor Violation in SUSY GUT Model with Non-universal Sfermion Masses
We analyze lepton flavor violating and processes in SUSY GUT model in which sfermions have special mass
spectrum. It is assumed that only third generation sfermions which are
contained in of SU(5) can have a different mass from
the others. This mass spectrum is led from GUT model with horizontal
symmetries. It is shown that branching ratios of and depend strongly on a right-handed stau mass. The weak scale
stability requires the light stau, so large decay rates can be expected in this
scenario. When stau is around 150 GeV and , the branching
ratios can be larger than and , which are within reach of future
experiments. In addition, this model has an interesting feature that the final
state charged lepton tends to have the right-handed chirality.Comment: 17 pages, 12 figures, v3 a reference adde
Determining the Neutrino Mass Hierarchy with Atmospheric Neutrinos
The possibility to determine the type of neutrino mass hierarchy by studying
atmospheric neutrino oscillations with a detector capable to distinguish
between neutrino and antineutrino events, such as magnetized iron calorimeters,
is considered. We discuss how the ability to distinguish between the neutrino
mass spectrum with normal and inverted hierarchy depends on detector
characteristics like neutrino energy and direction resolutions or charge
miss-identification, and on the systematical uncertainties related to the
atmospheric neutrino fluxes. We show also how the neutrino mass hierarchy
determination depends on the true values of and , as
well as on the type of the true hierarchy. We find that for -like events,
an accurate reconstruction of the energy and direction of the neutrino greatly
improves the sensitivity to the type of neutrino mass spectrum. For
and a precision of 5% in the reconstruction of
the neutrino energy and in the neutrino direction, the type of
neutrino mass hierarchy can be identified at the 2 C.L. with
approximately 200 events. For resolutions of 15% for the neutrino energy and
for the neutrino direction roughly one order of magnitude larger
event numbers are required. For a detector capable to distinguish between
and induced events the requirements on energy and direction
resolutions are, in general, less demanding than for a detector with muon
charge identification.Comment: 24 pages, 8 figure
Search for CP-violation in Positronium Decay
CP-violation in the quark sector has been well established over the last
decade, but has not been observed in the lepton sector. We search for
CP-violating decay processes in positronium, using the angular correlation of
(\vec{S}\cdot\vec{k_{1}})(\vec{S}\cdot\vec{k_{1}}\times\vec{k_{2}}), where
\vec{S} is the the positronium spin and \vec{k_{1}}, \vec{k_{2}} are the
directions of the positronium decay photons. To a sensitivity of
2.2\times10^{-3}, no CP-violation has been found, which is at the level of the
CP-violation amplitude in the K meson. A 90% confidence interval of the
CP-violation parameter (C_{CP}) was determined to be -0.0023 < C_{CP} < 0.0049.
This result is a factor 7 more strict than that of the previous experiment
Generalized quasiperiodic Rauzy tilings
We present a geometrical description of new canonical -dimensional
codimension one quasiperiodic tilings based on generalized Fibonacci sequences.
These tilings are made up of rhombi in 2d and rhombohedra in 3d as the usual
Penrose and icosahedral tilings. Thanks to a natural indexing of the sites
according to their local environment, we easily write down, for any
approximant, the sites coordinates, the connectivity matrix and we compute the
structure factor.Comment: 11 pages, 3 EPS figures, final version with minor change
Exchanges in complex networks: income and wealth distributions
We investigate the wealth evolution in a system of agents that exchange
wealth through a disordered network in presence of an additive stochastic
Gaussian noise. We show that the resulting wealth distribution is shaped by the
degree distribution of the underlying network and in particular we verify that
scale free networks generate distributions with power-law tails in the
high-income region. Numerical simulations of wealth exchanges performed on two
different kind of networks show the inner relation between the wealth
distribution and the network properties and confirm the agreement with a
self-consistent solution. We show that empirical data for the income
distribution in Australia are qualitatively well described by our theoretical
predictions.Comment: 8 pages, 11 figure
Update on the Pyramid Scheme
We summarize recent work in which we attempt to make a consistent model of
LHC physics, from the Pyramid Scheme. The models share much with the NMSSM, in
particular, enhanced tree level contributions to the Higgs mass and a
preference for small tan {\beta}. There are 3 different singlet fields, and a
new strongly coupled gauge theory, so the constraints of perturbative
unification are quite different. We outline our general approach to the model,
which contains a Kahler potential for three of the low energy fields, which is
hard to calculate. Detailed calculations, based on approximations to the Kahler
potential, will be presented in a future publication.Comment: LaTeX 2e/ 9 page
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