7,928 research outputs found
Collective treatment of High Energy Thresholds in SUSY - GUTs
Supersymmetric GUTs are the most natural extension of the Standard model
unifying electroweak and strong forces. Despite their indubitable virtues,
among these the gauge coupling unification and the quantization of the electric
charge, one of their shortcomings is the large number of parameters used to
describe the high energy thresholds (HET), which are hard to handle. We present
a new method according to which the effects of the HET, in any GUT model, can
be described by fewer parameters that are randomly produced from the original
set of the parameters of the model. In this way, regions favoured by the
experimental data are easier to locate, avoiding a detailed and time consuming
exploration of the parameter space, which is multidimensional even in the most
economic unifying schemes. To check the efficiency of this method, we directly
apply it to a SUSY SO(10) GUT model in which the doublet-triplet splitting is
realized through the Dimopoulos-Wilczek mechanism. We show that the demand of
gauge coupling unification, in conjunction with precision data, locates regions
of the parameter space in which values of the strong coupling \astrong are
within the experimental limits, along with a suppressed nucleon decay, mediated
by a higgsino driven dimension five operators, yielding lifetimes that are
comfortably above the current experimental bounds. These regions open up for
values of the SUSY breaking parameters m_0, M_1/2 < 1 TeV being therefore
accessible to LHC.Comment: 21 pages, 8 figures, UA-NPPS/BSM-10/02 (added
Modeling charge transport in Swept Charge Devices for X-ray spectroscopy
We present the formulation of an analytical model which simulates charge
transport in Swept Charge Devices (SCDs) to understand the nature of the
spectral redistribution function (SRF). We attempt to construct the
energy-dependent and position dependent SRF by modeling the photon interaction,
charge cloud generation and various loss mechanisms viz., recombination,
partial charge collection and split events. The model will help in optimizing
event selection, maximize event recovery and improve spectral modeling for
Chandrayaan-2 (slated for launch in 2014). A proto-type physical model is
developed and the algorithm along with its results are discussed in this paper.Comment: 9 pages, 7 figures, Proc. SPIE 8453, High Energy, Optical, and
Infrared Detectors for Astronomy
Flavor Gauge Models Below the Fermi Scale
The mass and weak interaction eigenstates for the quarks of the third
generation are very well aligned, an empirical fact for which the Standard
Model offers no explanation. We explore the possibility that this alignment is
due to an additional gauge symmetry in the third generation. Specifically, we
construct and analyze an explicit, renormalizable model with a gauge boson,
, corresponding to the symmetry of the third family. Having a
relatively light (in the MeV to multi-GeV range), flavor-nonuniversal gauge
boson results in a variety of constraints from different sources. By
systematically analyzing 20 different constraints, we identify the most
sensitive probes: kaon, , and Upsilon decays, mixing,
atomic parity violation, and neutrino scattering and oscillations. For the new
gauge coupling in the range the model is shown to
be consistent with the data. Possible ways of testing the model in physics,
top and decays, direct collider production and neutrino oscillation
experiments, where one can observe nonstandard matter effects, are outlined.
The choice of leptons to carry the new force is ambiguous, resulting in
additional phenomenological implications, such as non-universality in
semileptonic bottom decays. The proposed framework provides interesting
connections between neutrino oscillations, flavor and collider physics.Comment: 44 pages, 7 figures, 3 tables; B physics constraints and references
added, conclusions unchange
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