5,842 research outputs found

    Observation of coasting beam at the HERA Proton--Ring

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    We present data collected with the HERA-B wire target which prove the existence of coasting beam at the HERA proton storage ring. The coasting beam is inherently produced by the proton machine operation and is not dominated by target effects.Comment: 17 pages (Latex), 12 figures (Enc. Postscript

    Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 6: Accelerator Capabilities

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    These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 6, on Accelerator Capabilities, discusses the future progress of accelerator technology, including issues for high-energy hadron and lepton colliders, high-intensity beams, electron-ion colliders, and necessary R&D for future accelerator technologies.Comment: 26 page

    Prospects for the Search for a Standard Model Higgs Boson in ATLAS using Vector Boson Fusion

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    The potential for the discovery of a Standard Model Higgs boson in the mass range m_H < 2 m_Z in the vector boson fusion mode has been studied for the ATLAS experiment at the LHC. The characteristic signatures of additional jets in the forward regions of the detector and of low jet activity in the central region allow for an efficient background rejection. Analyses for the H -> WW and H -> tau tau decay modes have been performed using a realistic simulation of the expected detector performance. The results obtained demonstrate the large discovery potential in the H -> WW decay channel and the sensitivity to Higgs boson decays into tau-pairs in the low-mass region around 120 GeV.Comment: 20 pages, 13 ps figures, uses EPJ style fil

    Hierarchical Multimodel Ensemble Estimates of Soil Water Retention with Global Coverage

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    A correct quantification of mass and energy exchange processes among land surface and atmosphere requires an accurate description of unsaturated soil hydraulic properties. Soil pedotransfer functions (PTFs) have been widely used to predict soil hydraulic parameters. Here, 13 PTFs were grouped according to input data requirements and evaluated against a well-documented soil database with global coverage. Weighted ensembles (calibrated by four groups and the full 13-member set of PTFs) were shown to have improved performance over individual PTFs in terms of root mean square error and other model selection criteria. Global maps of soil water retention data from the ensemble models as well as their uncertainty were provided. These maps demonstrate that five PTF ensembles tend to have different estimates, especially in middle and high latitudes in the Northern Hemisphere. Our full 13-member ensemble model provides more accurate estimates than PTFs that are currently being used in earth system models

    Higgs After the Discovery: A Status Report

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    Recently, the ATLAS and CMS collaborations have announced the discovery of a 125 GeV particle, commensurable with the Higgs boson. We analyze the 2011 and 2012 LHC and Tevatron Higgs data in the context of simplified new physics models, paying close attention to models which can enhance the diphoton rate and allow for a natural weak-scale theory. Combining the available LHC and Tevatron data in the ZZ* 4-lepton, WW* 2-lepton, diphoton, and b-bbar channels, we derive constraints on the effective low-energy theory of the Higgs boson. We map several simplified scenarios to the effective theory, capturing numerous new physics models such as supersymmetry, composite Higgs, dilaton. We further study models with extended Higgs sectors which can naturally enhance the diphoton rate. We find that the current Higgs data are consistent with the Standard Model Higgs boson and, consequently, the parameter space in all models which go beyond the Standard Model is highly constrained.Comment: 37 pages; v2: ATLAS dijet-tag diphoton channel added, dilaton and doublet-singlet bugs corrected, references added; v3: ATLAS WW channel included, comments and references adde

    The Higgs Working Group: Summary Report (2001)

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    Report of the Higgs working group for the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001. It contains 7 separate sections: A. Theoretical Developments B. Higgs Searches at the Tevatron C. Experimental Observation of an invisible Higgs Boson at LHC D. Search for the Standard Model Higgs Boson using Vector Boson Fusion at the LHC E. Study of the MSSM channel A/HττA/H \to \tau \tau at the LHC F. Searching for Higgs Bosons in ttˉHt\bar t H Production G. Studies of Charged Higgs Boson Signals for the Tevatron and the LHCComment: 120 pages, latex, many figures, proceedings of the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001, full Author list included in paper. Typos corrected, author list and acknowledgements completed. Convernors: D. Cavalli, A. Djouadi, K. Jakobs, A. Nikitenko, M. Spira, C.E.M. Wagner, W.-M. Ya

    Excess Higgs Production in Neutralino Decays

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    The ATLAS and CMS experiments have recently claimed discovery of a Higgs boson-like particle at ~5 sigma confidence and are beginning to test the Standard Model predictions for its production and decay. In a variety of supersymmetric models, a neutralino NLSP can decay dominantly to the Higgs and the LSP. In natural SUSY models, a light third generation squark decaying through this chain can lead to large excess Higgs production while evading existing BSM searches. Such models can be observed at the 8 TeV LHC in channels exploiting the rare diphoton decays of the Higgs produced in the cascade decay. Identifying a diphoton resonance in association with missing energy, a lepton, or b-tagged jets is a promising search strategy for discovery of these models, and would immediately signal new physics involving production of a Higgs boson. We also discuss the possibility that excess Higgs production in these SUSY decays can be responsible for enhancements of up to 50% over the SM prediction for the observed rate in the existing inclusive diphoton searches, a scenario which would likely by the end of the 8 TeV run be accompanied by excesses in the diphoton + lepton/MET and SUSY multi-lepton/b searches and a potential discovery in a diphoton + 2b search.Comment: 42 pages, 19 figure

    Development and optimization of a new suspension system for lower limb prosthesis

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    The increasing rate of lower limb amputations reinforces the need to develop a new suspension system that provides a better quality of life for the lower limb amputees. This study aimed to present a novel suspension system that improves amputee’s satisfaction in terms of donning and doffing process of the prosthetic lower limb. The design of the proposed suspension system was developed following the design methodology, to establish the amputee’s needs, objectives, functions, requirements and specifications in order to op-timize the final solution. The final solution is a combination of a guiding and fixation mechanisms that improve the donning and doffing process by driv-ing the serrated pin to the fixation system. The proposed suspension system is a good alternative to improve the quality of life of amputees with lower activity level on the daily basis.(undefined

    Distinguishing Various Models of the 125 GeV Boson in Vector Boson Fusion

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    The hint of a new particle around 125 GeV at the LHC through the decay modes of diphoton and a number of others may point to quite a number of possibilities. While at the LHC the dominant production mechanism for the Higgs boson of the standard model and some other extensions is via the gluon fusion process, the alternative vector boson fusion is more sensitive to electroweak symmetry breaking through the gauge-Higgs couplings and therefore can be used to probe for models beyond the standard model. In this work, using the well known dijet-tagging technique to single out the vector boson fusion mechanism, we investigate its capability to discriminate a number of models that have been suggested to give an enhanced inclusive diphoton production rate, including the standard model Higgs boson, fermiophobic Higgs boson, Randall-Sundrum radion, inert-Higgs-doublet model, two-Higgs-doublet model, and the MSSM. The rates in vector-boson fusion can give more information of the underlying models to help distinguishing among the models.Comment: 31 pages, 3 figures; in this version some wordings are change
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