6,059 research outputs found

    Summary of the CMS Discovery Potential for the MSSM SUSY Higgses

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    This work summarises the present understanding of the expected MSSM SUSY Higgs reach for CMS. Many of the studies presented here result from detailed detector simulations incorporating final CMS detector design and response. With 30 fb-1 the h -> gamma,gamma and h -> bb channels allow to cover most of the MSSM parameter space. For the massive A,H,H+ MSSM Higgs states the channels A,H -> tau,tau and H+ -> tau,nu turn out to be the most profitable ones in terms of mass reach and parameter space coverage. Consequently CMS has made a big effort to trigger efficiently on taus. Provided neutralinos and sleptons are not too heavy, there is an interesting complementarity in the reaches for A,H -> tau,tau and A,H -> chi,chi.Comment: 19 pages, 27 figure

    Muon Track Matching

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    For most physical processes the tracks observed in the muon stations must be matched with the corresponding tracks in the inner tracker, the external muon system providing muon identification and triggering but the tracker points giving the precise momentum measurement at lower momenta. For high momenta the momentum resolution is much improved by the interconnection of inner and outer measurements. The matching of outer and inner measurements is more delicate in case of muons embedded in jets. A study of the matching procedure was carried out using samples of (b, anti b) jets at high Pt, requiring (b, anti b) -> mu decays.For most physical processes the tracks observed in the muon stations must be matched with the corresponding tracks in the inner tracker, the external muon system providing muon identification and triggering but the tracker points giving the precise momentum measurement at lower momenta. For high momenta the momentum resolution is much improved by the interconnection of inner and outer measurements. The matching of outer and inner measurements is more delicate in case of muons embedded in jets. A study of the matching procedure was carried out using samples of (b, anti b) jets at high Pt, requiring (b, anti b) -> mu decays

    Multimodality imaging of chronic tophaceous gout

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    The diagnosis of gout is usually based on clinical presentation and laboratory findings. Imaging plays a role in the assessment and grading of articular damage related to chronic, long-standing disease, which is characterized by granulomatous synovitis, tophi, and erosions. Multimodality imaging of chronic tophaceous gout may be useful in clinical practice for a variety of purposes, including assessment of disease-related anatomical changes and monitoring of articular and soft-tissue lesions over time, especially in response to urate-lowering therapy. Radiography remains the primary imaging technique. Ultrasonography may detect monosodium urate crystals on cartilage, is helpful to assess small joint effusion, to guide to joint aspiration, and to evaluate the volume of tophi. Computed tomography is considered to be more sensitive than plain radiography in the detection and evaluation of cortical bone erosions associated with tophi. MRI represents the only imaging modality which provides visualization of bone marrow oedema associated with erosions and may be useful to characterize and distinguish tophi from other soft tissue nodules

    Next-to-leading order QCD corrections to W+W- production via vector-boson fusion

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    Vector-boson fusion processes constitute an important class of reactions at hadron colliders, both for signals and backgrounds of new physics in the electroweak interactions. We consider what is commonly referred to as W+W- production via vector-boson fusion (with subsequent leptonic decay of the Ws), or, more precisely, e+ nu_e mu- nubar_mu + 2 jets production in proton-proton scattering, with all resonant and non-resonant Feynman diagrams and spin correlations of the final-state leptons included, in the phase-space regions which are dominated by t-channel electroweak-boson exchange. We compute the next-to-leading order QCD corrections to this process, at order alpha^6 alpha_s. The QCD corrections are modest, changing total cross sections by less than 10%. Remaining scale uncertainties are below 2%. A fully-flexible next-to-leading order partonic Monte Carlo program allows to demonstrate these features for cross sections within typical vector-boson-fusion acceptance cuts. Modest corrections are also found for distributions.Comment: 29 pages, 14 figure

    Dark Matter and LHC: What is the Connection?

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    We review what can (and cannot) be learned if dark matter is detected in one or more experiments, emphasizing the importance of combining LHC data with direct, astrophysical and cosmological probes of dark matter. We briefly review the conventional picture of a thermally produced WIMP relic density and its connection with theories of electroweak symmetry breaking. We then discuss both experimental and theoretical reasons why one might generically expect this picture to fail. If this is the case, we argue that a combined effort bringing together all types of data -- combined with explicitly constructed theoretical models -- will be the only way to achieve a complete understanding of the dark matter in our universe and become confident that any candidate actually provides the relic density.Comment: 25 pages, 2 figures, Invited review for Modern Physics Letters

    Human proliferating cell nuclear antigen, poly(ADP-ribose) polymerase-1, and p21waf1/cip1. A dynamic exchange of partners.

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    We addressed the analysis of the physical and functional association of proliferating cell nuclear antigen (PCNA), a protein involved in many DNA transactions, with poly(ADP-ribose) polymerase (PARP-1), an enzyme that plays a crucial role in DNA repair and interacts with many DNA replication/repair factors. We demonstrated that PARP-1 and PCNA co-immunoprecipitated both from the soluble and the DNA-bound fraction isolated from S-phase-synchronized HeLa cells. Immunoprecipitation experiments with purified proteins further confirmed a physical association between PARP-1 and PCNA. To investigate the effect of this association on PARP-1 activity, an assay based on the incorporation of radioactive NAD was performed. Conversely, the effect of PARP-1 on PCNA-dependent DNA synthesis was assessed by a DNA polymerase delta assay. A marked inhibition of both reactions was found. Unexpectedly, PARP-1 activity also decreased in the presence of p21waf1/cip1. By pull-down experiments, we provided the first evidence for an association between PARP-1 and p21, which involves the C-terminal part of p21 protein. This association was further demonstrated to occur also in vivo in MNNG (N-methyl-N'-nitro-N-nitrosoguanidine)-treated human fibroblasts. These observations suggest that PARP-1 and p21 could cooperate in regulating the functions of PCNA during DNA replication/repair

    Charged Higgs production from SUSY particle cascade decays at the LHC

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    We analyze the cascade decays of the scalar quarks and gluinos of the Minimal Supersymmetric extension of the Standard Model, which are abundantly produced at the Large Hadron Collider, into heavier charginos and neutralinos which then decay into the lighter ones and charged Higgs particles, and show that they can have substantial branching fractions. The production rates of these Higgs bosons can be much larger than those from the direct production mechanisms, in particular for intermediate values of the parameter tanβ\tan \beta, and could therefore allow for the detection of these particles. We also discuss charged Higgs boson production from direct two-body top and bottom squark decays as well as from two- and three-body gluino decays.Comment: 30 pages with 10 figures, latex. Uses axodraw.sty and epsfig.st

    Wide Bandgap Perovskite Photovoltaic Cells for Stray Light Recycling in a System Emitting Broadband Polarized Light

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    Perovskite based photovoltaic (PV) cells are unique in combining low open-circuit voltage losses with a broad bandgap tunability. This makes them an ideal PV cell to recycle photons back into electrical power in a variety of illumination systems or light emitting devices. Here, advantage of these features is taken and wide bandgap (WBG) perovskite PV cells are incorporated in devices suitable for display illumination and demonstrate a high yield in stray light recycling back into electricity with up to a 37.5% power conversion efficiency. The specific device considered is a modified half-cylinder photonic plate designed to emit diffused broadband polarized light using a nonabsorbing reflective polarizer based on a random dielectric layer distribution. It is experimentally demonstrated that light recycling using appropriately tuned WBG perovskite PV cells becomes very efficient when implemented in systems where the light is emitted from narrowband sources, even if the emission spans a broad wavelength range
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