872 research outputs found

    The running coupling method with next-to-leading order accuracy and pion, kaon elm form factors

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    The pion and kaon electromagnetic form factors FM(Q2)F_M(Q^2) are calculated at the leading order of pQCD using the running coupling constant method. In calculations the leading and next-to-leading order terms in αS((1x)(1y)Q2)\alpha_S((1-x)(1-y)Q^2) expansion in terms of αS(Q2)\alpha_S(Q^2) are taken into account. The resummed expression for FM(Q2)F_M(Q^2) is found. Results of numerical calculations for the pion (asymptotic distribution amplitude) are presented.Comment: 9 pages, 1 figur

    Exclusive high-Q2Q^2 electroproduction: light-cone wave functions and electromagnetic form factors of mesons,

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    We apply the light-cone technique to electroproduction reaction epeπ+nep\to e\pi^+n long considered as a means of measuring the electromagnetic form factor of the pion. We show that the interpretation of the long-standing puzzle of large transverse cross section (σT\sigma_T) in terms of the γρπ\gamma^*\rho\to \pi transition on the ρ\rho mesons in the light-cone proton is possible, but requires quite a slow decrease of the F_{\rho\pi}(\q2) form factor. This interpretation can be tested in the related epeπ0pep\to e\pi^0p reaction. Corrections which are due to the final-state meson-baryon interactions (FSI) are evaluated and are shown to amount to a 25%25\% effect at moderately large \q2. Vanishing FSI with increasing Q2Q^2 - the color transparency phenomenon - is shown to be very strong

    SNAP satellite focal plane development

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    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics

    Pion Form Factor in the NLC QCD SR approach

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    We present results of a calculation of the electromagnetic pion form factor within a framework of QCD Sum Rules with nonlocal condensates and using a perturbative spectral density which includes \mathcal{O}(\alpha_s) contributions.Comment: 9 pages, 2 figures (embedded). Talk presented by the second author at the Workshop on Physics of Fundamental Interactions, Institute of High Energy Physics, Protvino, Russia, 22--25 December 200

    Pseudovector components of the pion, pi^0 -> gamma gamma, and F_pi(q^2)

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    As a consequence of dynamical chiral symmetry breaking the pion Bethe-Salpeter amplitude necessarily contains terms proportional to gamma_5 gamma.P and gamma_5 gamma.k, where k is the relative and P the total momentum of the constituents. These terms are essential for the preservation of low energy theorems, such as the Gell-Mann--Oakes-Renner relation and those describing anomalous decays of the pion, and to obtaining an electromagnetic pion form factor that falls as 1/q^2 for large q^2, up to calculable ln(q^2)-corrections. In a simple model, which correlates low- and high-energy pion observables, we find q^2 F_pi(q^2) ~ 0.12 - 0.19 GeV^2 for q^2 >~10 GeV^2.Comment: 15 pages, 2 figures, REVTE

    Active cooling control of the CLEO detector using a hydrocarbon coolant farm

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    We describe a novel approach to particle-detector cooling in which a modular farm of active coolant-control platforms provides independent and regulated heat removal from four recently upgraded subsystems of the CLEO detector: the ring-imaging Cherenkov detector, the drift chamber, the silicon vertex detector, and the beryllium beam pipe. We report on several aspects of the system: the suitability of using the aliphatic-hydrocarbon solvent PF(TM)-200IG as a heat-transfer fluid, the sensor elements and the mechanical design of the farm platforms, a control system that is founded upon a commercial programmable logic controller employed in industrial process-control applications, and a diagnostic system based on virtual instrumentation. We summarize the system's performance and point out the potential application of the design to future high-energy physics apparatus.Comment: 21 pages, LaTeX, 5 PostScript figures; version accepted for publication in Nuclear Instruments and Methods in Physics Research

    Person localization using sensor information fusion

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    Nowadays the incredible grow of mobile devices market led to the need for location-aware applications. However, sometimes person location is di cult to obtain, since most of these devices only have a GPS (Global Positioning System) chip to retrieve location. In order to sup- press this limitation and to provide location everywhere (even where a structured environment doesn't exist) a wearable inertial navigation sys- tem is proposed, which is a convenient way to track people in situations where other localization systems fail. The system combines pedestrian dead reckoning with GPS, using widely available, low-cost and low-power hardware components. The system innovation is the information fusion and the use of probabilistic methods to learn persons gait behavior to correct, in real-time, the drift errors given by the sensors.This work is part-funded by ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT Fundao para a Cincia e a Tecnologia (Portuguese Foundation for Science and Technology) within project FCOMP-01-0124-FEDER- 028980 (PTDC/EEI-SII/1386/2012). Ricardo also acknowledge FCT for the support of his work through the PhD grant (SFRH/DB/70248/2010)

    Light-cone QCD Sum Rules for the Λ\Lambda Baryon Electromagnetic Form Factors and its magnetic moment

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    We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the Λ\Lambda baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is μΛ=(0.64±0.04)μN\mu_\Lambda=-(0.64\pm0.04)\mu_N, which is in accordance with the experimental data and the existing theoretical results. We find that it is twist 4 but not the leading twist distribution amplitudes that dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.

    Does J/ψπ+πJ/\psi \rightarrow \pi^{+} \pi^{-} fix the Electromagnetic Form Factor Fπ(t)F_{\pi}(t) at t=MJ/ψ2t=M_{J/\psi}^2?

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    We show that the J/ψπ+πJ/\psi \rightarrow \pi^{+} \pi^{-} decay is a reliable source of information for the electromagnetic form factor of the pion at t=MJ/ψ2=9.6GeV2t=M_{J/\psi}^2=9.6 {\rm GeV}^2 by using general arguments to estimate, or rather, put upper bounds on, the background processes that could spoil this extraction. We briefly comment on the significance of the resulting Fπ(MJ/ψ2)F_{\pi}(M_{J/\psi}^2).Comment: 10 pages revtex manuscript, one figure--not included, U. of MD PP #94-00
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