5,701 research outputs found
All Possible Lightest Supersymmetric Particles in R-Parity Violating mSUGRA Models and their Signals at the LHC
We consider minimal supergravity (mSUGRA) models with an additional R-parity
violating operator at the grand unification scale. This can change the
supersymmetric spectrum leading on the one hand to a sneutrino, smuon or squark
as the lightest supersymmetric particle (LSP). On the other hand, a wide
parameter region is reopened, where the scalar tau is the LSP. It is vital to
know the nature of the LSP, because supersymmetric particles normally cascade
decay down to the LSP at collider experiments. We investigate in detail the
conditions leading to non-neutralino LSP scenarios. We also present some
typical LHC signatures.Comment: 4 pages, 4 figures, submitted for the proceedings of the SUSY09
conferenc
Spatio-temporal attributes of water temperature and macroinvertebrate assemblages in the headwaters of the Bushmans River, southern Drakensberg
Currently, there is little understanding of the controls that instream thermal limits and hydraulic biotype diversity have on macroinvertebrate assemblages, particularly in association with changing altitude within given southern African mountain drainage systems. Thus, the aim of this research was to examine aquatic macroinvertebrate assemblage changes in response to spatial and temporal geo-hydrological contexts (temperature and hydraulic biotype) along the upper Bushmans River, southern Drakensberg. Instream temperature was continuously logged at 3 altitudes (1 760, 2 030, 2 280 m amsl) along the Bushmans River to the east of the Great Escarpment, and in the headwaters of the Sani River (2 860 m amsl) to the west of the escarpment, for the period January–May 2007. Aquatic macroinvertebrates were sampled during early December 2006, late March 2007, and late May 2007. The study demonstrates that decreasing water temperatures, both spatially (with increasing altitude) and seasonally (from summer to winter), and/or decreasing diversity of hydraulic biotypes associated with stream-channel narrowing in Drakensberg rivers/streams, are associated with a general decrease in the absolute number of macroinvertebrate families, a lower dissimilarity coefficient along the Bushmans River altitudinal transect, and a decreasing variance in the numbers of macroinvertebrate families across various hydraulic biotypes.Keywords: Aquatic macroinvertebrates, water temperature, hydraulic biotypes, Drakensber
Stau as the Lightest Supersymmetric Particle in R-Parity Violating SUSY Models: Discovery Potential with Early LHC Data
We investigate the discovery potential of the LHC experiments for R-parity
violating supersymmetric models with a stau as the lightest supersymmetric
particle (LSP) in the framework of minimal supergravity. We classify the final
states according to their phenomenology for different R-parity violating decays
of the LSP. We then develop event selection cuts for a specific benchmark
scenario with promising signatures for the first beyond the Standard Model
discoveries at the LHC. For the first time in this model, we perform a detailed
signal over background analysis. We use fast detector simulations to estimate
the discovery significance taking the most important Standard Model backgrounds
into account. Assuming an integrated luminosity of 1 inverse femtobarn at a
center-of-mass energy of 7 TeV, we perform scans in the parameter space around
the benchmark scenario we consider. We then study the feasibility to estimate
the mass of the stau-LSP. We briefly discuss difficulties, which arise in the
identification of hadronic tau decays due to small tau momenta and large
particle multiplicities in our scenarios.Comment: 26 pages, 18 figures, LaTeX; minor changes, final version published
in PR
Sneutrino as Lightest Supersymmetric Particle in B3 mSUGRA Models and Signals at the LHC
We consider B3 mSUGRA models where we have one lepton number violating LQD
operator at the GUT scale. This can alter the supersymmetric mass spectrum
leading to a sneutrino as the lightest supersymmetric particle in a large
region of parameter space. We take into account the restrictions from neutrino
masses, the muon anomalous magnetic moment, b -> s gamma and other precision
measurements. We furthermore investigate existing restrictions from direct
searches at LEP, the Tevatron and the CERN p\bar p collider. We then give
examples for characteristic signatures at the LHC.Comment: 22 pages, 11 figure
Light Stop Searches at the LHC in Events with two b-Jets and Missing Energy
We propose a new method to discover light top squarks (stops) in the
co-annihilation region at the Large Hadron Collider (LHC). The bino-like
neutralino is the lightest supersymmetric particle (LSP) and the lighter stop
is the next-to-LSP. Such scenarios can be consistent with electroweak
baryogenesis and also with dark matter constraints. We consider the production
of two stops in association with two b-quarks, including pure QCD as well as
mixed electroweak-QCD contributions. The stops decay into a charm quark and the
LSP. For a higgsino-like light chargino the electroweak contributions can
exceed the pure QCD prediction. We show the size of the electroweak
contributions as a function of the stop mass and present the LHC discovery
reach in the stop-neutralino mass plane.Comment: 12 pages, 10 figure
Performance House -- A Cold Climate Challenge Home
Working with builder partners on a test homes allows for vetting of whole-house building strategies to eliminate any potential unintended consequences prior to implementing these solution packages on a production scale. To support this research, CARB partnered with Preferred Builders Inc. on a high-performance test home in Old Greenwich, CT. The philosophy and science behind the 2,700 ft2 'Performance House' was based on the premise that homes should be safe, healthy, comfortable, durable, efficient, and adapt with the homeowners. The technologies and strategies used in the 'Performance House' were not cutting-edge, but simply 'best practices practiced'. The focus was on simplicity in construction, maintenance, and operation. When seeking a 30% source energy savings targets over a comparable 2009 IECC code-built home in the cold climate zone, nearly all components of a home must be optimized. Careful planning and design are critical. To help builders and architects seeking to match the performance of this home, a step-by-step guide through the building shell components of DOE's Challenge Home are provided in a pictorial story book. The end result was a DOE Challenge Home that achieved a HERS Index Score of 20 (43 without PV, the minimum target was 55 for compliance). This home was also awarded the 2012 HOBI for Best Green Energy Efficient Home from the Home Builders & Remodelers Association of Connecticut
Supersymmetric NLO QCD Corrections to Resonant Slepton Production and Signals at the Tevatron and the LHC
We compute the total cross section and the transverse momentum distribution
for single charged slepton and sneutrino production at hadronic colliders
including NLO supersymmetric and non-supersymmetric QCD corrections. The
supersymmetric QCD corrections can be substantial. We also resum the gluon
transverse momentum distribution and compare our results with two Monte Carlo
generators. We compute branching ratios of the supersymmetric decays of the
slepton and determine event rates for the like-sign dimuon final state at the
Tevatron and at the LHC.Comment: 14 pages, LaTeX, 8 figures, uses REVTex
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