1,208 research outputs found
Multicomponent Dark Matter in Supersymmetric Hidden Sector Extensions
Most analyses of dark matter within supersymmetry assume the entire cold dark
matter arising only from weakly interacting neutralinos. We study a new class
of models consisting of hidden sector extensions of the MSSM that
includes several stable particles, both fermionic and bosonic, which can be
interpreted as constituents of dark matter. In one such class of models, dark
matter is made up of both a Majorana dark matter particle, i.e., a neutralino,
and a Dirac fermion with the current relic density of dark matter as given by
WMAP being composed of the relic density of the two species. These models can
explain the PAMELA positron data and are consistent with the anti-proton flux
data, as well as the photon data from FERMI-LAT. Further, it is shown that such
models can also simultaneously produce spin independent cross sections which
can be probed in CDMS-II, XENON-100 and other ongoing dark matter experiments.
The implications of the models at the LHC and at the NLC are also briefly
discussed.Comment: Journal: Physical Review D, Latex 32 pages, 4 eps figure
Higgs Boson Mass Predictions in SUGRA Unification, Recent LHC-7 Results, and Dark Matter
LHC-7 has narrowed down the mass range of the light Higgs boson. This result
is consistent with the supergravity unification framework, and the current
Higgs boson mass window implies a rather significant loop correction to the
tree value pointing to a relatively heavy scalar sparticle spectrum with
universal boundary conditions. It is shown that the largest value of the Higgs
boson mass is obtained on the Hyperbolic Branch of radiative breaking. The
implications of light Higgs boson in the broader mass range of 115 GeV to 131
GeV and a narrower range of 123 GeV to 127 GeV are explored in the context of
the discovery of supersymmetry at LHC-7 and for the observation of dark matter
in direct detection experiments.Comment: 8 pages, 5 figure
Low Mass Gluino within the Sparticle Landscape, Implications for Dark Matter, and Early Discovery Prospects at LHC-7
We analyze supergravity models that predict a low mass gluino within the
landscape of sparticle mass hierarchies. The analysis includes a broad class of
models that arise in minimal and in non-minimal supergravity unified frameworks
and in extended models with additional hidden sector gauge
symmetries. Gluino masses in the range GeV are investigated. Masses
in this range are promising for early discovery at the LHC at TeV
(LHC-7). The models exhibit a wide dispersion in the gaugino-Higgsino
eigencontent of their LSPs and in their associated sparticle mass spectra. A
signature analysis is carried out and the prominent discovery channels for the
models are identified with most models needing only for
discovery at LHC-7. In addition, significant variations in the discovery
capability of the low mass gluino models are observed for models in which the
gluino masses are of comparable size due to the mass splittings in different
models and the relative position of the light gluino within the various
sparticle mass hierarchies. The models are consistent with the current
stringent bounds from the Fermi-LAT, CDMS-II, XENON100, and EDELWEISS-2
experiments. A subclass of these models, which include a mixed-wino LSP and a
Higgsino LSP, are also shown to accommodate the positron excess seen in the
PAMELA satellite experiment.Comment: 37 pages, 8 figures, Published in PR
Excess Observed in CDF and SUSY at the LHC
The recent excess observed by CDF in is
interpreted in terms of a possible supersymmetric origin. An analysis is given
of the parameter space of mSUGRA and non-universal SUGRA models under the
combined constraints from LHC-7 with 165 pb of integrated luminosity,
under the new XENON-100 limits on the neutralino-proton spin independent cross
section and under the CDF 90% C.L. limit reported
to arise from an excess number of dimuon events. It is found that the predicted
value of the branching ratio consistent with all
the constraints contains the following set of NLSPs: chargino, stau, stop or CP
odd (even) Higgs. The lower bounds of sparticles, including those from the LHC,
XENON and CDF constraint, are exhibited and the shift in
the allowed range of sparticle masses arising solely due to the extra
constraint from the CDF result is given. It is pointed out that the two sided
CDF 90% C.L. limit puts upper bounds on sparticle masses. An analysis of
possible signatures for early discovery at the LHC is carried out corresponding
to the signal region in . Implications of GUT-scale
non-universalities in the gaugino and Higgs sectors are discussed. If the
excess seen by the CDF Collaboration is supported by further data from LHCb or
D0, this new result could be a harbinger for the discovery of supersymmetry.Comment: References added, text update
Interpreting the First CMS and ATLAS SUSY Results
The CMS and the ATLAS Collaborations have recently reported on the search for
supersymmetry with 35 pb of data and have put independent limits on the
parameter space of the supergravity unified model with universal boundary
conditions at the GUT scale for soft breaking, i.e., the mSUGRA model. We
extend this study by examining other regions of the mSUGRA parameter space in
and . Further, we contrast the reach of CMS and ATLAS with 35
pb of data with the indirect constraints, i.e., the constraints from the
Higgs boson mass limits, from flavor physics and from the dark matter limits
from WMAP. Specifically it is found that a significant part of the parameter
space excluded by CMS and ATLAS is essentially already excluded by the indirect
constraints and the fertile region of parameter space has yet to be explored.
We also emphasize that gluino masses as low as 400 GeV but for squark masses
much larger than the gluino mass remain unconstrained and further that much of
the hyperbolic branch of radiative electroweak symmetry breaking, with low
values of the Higgs mixing parameter , is essentially untouched by the
recent LHC analysis.Comment: 3 figure panels, 10 plot
A Jurassic (Bathonian-Callovian) Daghanirhynchia brachiopod fauna from Jordan
A Jurassic (Bathonian-Callovian) brachiopod fauna from Jordan consists of seven rhynchonellid species all belonging to the genus Daghanirhynchia of which two are new: Daghanirhynchia rawyaensis and D. jordanica. Emended diagnoses are given for Daghanirhynchia daghaniensis and D. macfadyeni. Additional taxa described include Daghanirhynchia angulocostata, D. susanae and D. triangulata. Threedimensional reconstructions illustrate the internal morphology of the articulated shells for the first time in this genus. The material studied herein was collected from Wadi Zarqa in northwestern Jordan, almost due north of the Dead Sea, and to the east of the Rift Valley. Most species seem to be geographically restricted within the Jurassic Ethiopian Province, however specimens from Somalia and Ethiopia are larger in size than in other parts of the Province and shell size increases in stratigraphically younger specimens. The occurrence of Daghanirhynchia in India is the only appearance of the genus outside the Ethiopian Province
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