205 research outputs found
Viable models with non-universal gaugino mediated supersymmetry breaking
Recently, extra dimensional SUSY GUT models have been proposed in which
compactification of the extra dimension(s) leads to a breakdown of the gauge
symmetry and/or supersymmetry. We examine a particular class of
higher-dimensional models exhibiting supersymmetry and SU(5) or SO(10) GUT
symmetry. SUSY breaking occurs on a hidden brane, and is communicated to the
visible brane via gaugino mediation. Non-universal gaugino masses are developed
at the compactification scale as a consequence of a restricted gauge symmetry
on the hidden brane. In this case, the compactification scale is at or slightly
below the GUT scale. We examine the parameter space of such models where
gaugino masses are related due to a Pati-Salam symmetry on the hidden brane. We
find limited but significant regions of model parameter space where a viable
spectra of SUSY matter is generated. Our results are extended to the more
general case of three independent gaugino masses; here we find that large
parameter space regions open up for large values of the U(1) gaugino mass M_1.
We also find the relic density of neutralinos for these models to be generally
below expectations from cosmological observations, thus leaving room for hidden
sector states to make up the bulk of cold dark matter. Finally, we evaluate the
branching fraction BF(b -> s gamma) and muon anomalous magnetic moment a_\mu.Comment: 21 pages, 9 figure
Diagnosing Spin at the LHC via Vector Boson Fusion
We propose a new technique for determining the spin of new massive particles
that might be discovered at the Large Hadron Collider. The method relies on
pair-production of the new particles in a kinematic regime where the vector
boson fusion production mechanism is enhanced. For this regime, we show that
the distribution of the leading jets as a function of their relative azimuthal
angle can be used to distinguish spin-0 from spin-1/2 particles. We illustrate
this effect by considering the particular cases of (i) strongly-interacting,
stable particles and (ii) supersymmetric particles carrying color charge. We
argue that this method should be applicable in a wide range of new physics
scenarios.Comment: 5 pages, 4 figure
A solution to the mu problem in the presence of a heavy gluino LSP
In this paper we present a solution to the problem in an SO(10)
supersymmetric grand unified model with gauge mediated and D-term supersymmetry
breaking. A Peccei-Quinn symmetry is broken at the messenger scale GeV and enables the generation of the term. The boundary
conditions defined at lead to a phenomenologically acceptable version of
the minimal supersymmetric standard model with novel particle phenomenology.
Either the gluino or the gravitino is the lightest supersymmetric particle
(LSP). If the gravitino is the LSP, then the gluino is the next-to-LSP (NLSP)
with a lifetime on the order of one month or longer. In either case this heavy
gluino, with mass in the range 25 - 35 GeV, can be treated as a stable particle
with respect to experiments at high energy accelerators. Given the extensive
phenomenological constraints we show that the model can only survive in a
narrow region of parameter space resulting in a light neutral Higgs with mass
GeV and . In addition the lightest stop
and neutralino have mass GeV and GeV,
respectively. Thus the model will soon be tested. Finally, the invisible axion
resulting from PQ symmetry breaking is a cold dark matter candidate.Comment: 30 pages, 9 figure
Ultra High Energy Cosmic Rays from Sequestered X Bursts
Assuming that there is no GZK (Greisen-Zatsepin-Kuzmin) cut-off and that
super-GZK cosmic rays correlate with AGN (Active Galactic Nuclei) at
cosmological distances, it is speculated that a relic superheavy particle (X)
has its lifetime enhanced by sequestration in an extra dimension. This
sequestration is assumed to be partially liberated by proximity of merging
supermassive black holes in an AGN, temporarily but drastically reducing the
lifetime, thus stimulating an X burst. Based on sequestration of the decay
products of X, a speculative explanation of the observed ratio is
proposed.Comment: 12 pages LaTe
Where the Sidewalk Ends: Jets and Missing Energy Search Strategies for the 7 TeV LHC
This work explores the potential reach of the 7 TeV LHC to new colored states
in the context of simplified models and addresses the issue of which search
regions are necessary to cover an extensive set of event topologies and
kinematic regimes. This article demonstrates that if searches are designed to
focus on specific regions of phase space, then new physics may be missed if it
lies in unexpected corners. Simple multiregion search strategies can be
designed to cover all of kinematic possibilities. A set of benchmark models are
created that cover the qualitatively different signatures and a benchmark
multiregion search strategy is presented that covers these models.Comment: 30 pages, 8 Figures, 3 Tables. Version accepted at JHEP. Minor
changes. Added figur
Single gluino production in the R-parity lepton number violating MSSM at the LHC
We examine the -violating signal of single gluino production
associated with a charged lepton or neutrino at the large hadron collider
(LHC), in the model of R-parity relaxed supersymmetric model. If the parameters
in the supersymmetric interactions are not too small, and the
mass of gluino is considered in the range from several GeV (as the Lightest
Supersymmetric Particle) to 800 GeV, the cross section of the single gluino
production via Drell-Yan processes can be in the order of
femto barn, and that via gluon fusion in the order of femto
barn. If the gluino decay can be well detected in the CERN LHC, this process
provides a prospective way to probe supersymmetry and violation.Comment: LaTex, 22 pages, 5 EPS file
Tendinopathy—from basic science to treatment
Chronic tendon pathology (tendinopathy), although common, is difficult to treat. Tendons possess a highly organized fibrillar matrix, consisting of type I collagen and various 'minor' collagens, proteoglycans and glycoproteins. The tendon matrix is maintained by the resident tenocytes, and there is evidence of a continuous process of matrix remodeling, although the rate of turnover varies at different sites. A change in remodeling activity is associated with the onset of tendinopathy. Major molecular changes include increased expression of type III collagen, fibronectin, tenascin C, aggrecan and biglycan. These changes are consistent with repair, but they might also be an adaptive response to changes in mechanical loading. Repeated minor strain is thought to be the major precipitating factor in tendinopathy, although further work is required to determine whether it is mechanical overstimulation or understimulation that leads to the change in tenocyte activity. Metalloproteinase enzymes have an important role in the tendon matrix, being responsible for the degradation of collagen and proteoglycan in both healthy patients and those with disease. Metalloproteinases that show increased expression in painful tendinopathy include ADAM (a disintegrin and metalloproteinase)-12 and MMP (matrix metalloproteinase)-23. The role of these enzymes in tendon pathology is unknown, and further work is required to identify novel and specific molecular targets for therapy
Rehabilitation following proximal humeral fracture in the UK National Health Service: a survey of publicly facing information
© 2020 John Wiley & Sons Ltd. Introduction: Proximal humeral fractures (PHF) are a common injury in the older population but there is limited research evaluating rehabilitation following PHF. The aim of this study was to understand current National Health Service (NHS) practice for rehabilitation following PHF as a platform for conducting future research. Methods: Two reviewers independently undertook electronic searches for publicly available information sheets (PIS) from websites of NHS Trusts that included detail about rehabilitation following PHF, for example, duration of immobilisation. One reviewer extracted data and a second reviewer verified this. Results: Seventeen PIS from 17 different NHS trusts were identified. All provided some information on the method of immobilisation but only six provided guidance on duration of immobilisation with the median time being 2 weeks (range 0–6). The median time to commencement of passive exercise was 2 weeks (range 0–4) and 9 weeks (range 6–12) for active exercise. Only one PIS reported on the time for commencement of resisted exercises and this was reported as 6 weeks. The median time recommended return to work was 7.5 weeks (range 6–12). Conclusion: This study found limited publicly available information for rehabilitation following PHF in the NHS but offers some insight into current approaches. Our results will facilitate development of relevant information for patients and evaluation of rehabilitation strategies in future research
An Updated Description of Heavy-Hadron Interactions in Geant-4
Exotic stable massive particles (SMP) are proposed in a number of scenarios
of physics beyond the Standard Model. It is important that LHC experiments are
able both to detect and extract the quantum numbers of any SMP with masses
around the TeV scale. To do this, an understanding of the interactions of SMPs
in matter is required. In this paper a Regge-based model of R-hadron scattering
is extended and implemented in Geant-4. In addition, the implications of
-hadron scattering for collider searches are discussed
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