15,907 research outputs found

    Towards an Understanding of the New Charm and Charm-Strange Mesons

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    The observation of the D_{sJ}^*(2317), D_{sJ}(2460), and SELEX D^*_{sJ}(2632) states with properties differing considerably from what was expected has led to a renewed interest in hadron spectroscopy. In addition to these states, non-strange partners of the D_{sJ} states have also been observed. Understanding the D_0^* and D_1' states can provide important insights into the D_{sJ} states. In this contribution I examine quark model predictions for the D_0^* and D_1' states and discuss experimental measurements that can shed light on them. I find that these states are well described as the broad, j=1/2 non-strange charmed P-wave mesons. In the latter part of this writeup I discuss the c bar{s} possibilities for the SELEX D^*_{sJ}(2632) and measurements that can shed light on it.Comment: Talk presented at the 1st Meeting of the APS Topical Group on Hadronic Physics (Fermilab, Oct 24-26, 2004). 4 pages uses jpcon

    Leptoquark Production and Identification at High Energy Lepton Colliders

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    Leptoquarks can be produced in substantial numbers for masses very close to the collider centre of mass energy in e+ee^+e^-, eγe\gamma, and μ+μ\mu^+\mu^- collisions due to the quark content of the photon resulting in equivalently high discovery limits. Using polarization asymmetries in an eγe\gamma collider the ten different types of leptoquarks listed by Buchm\"uller, R\"uckl and Wyler can be distinquished from one another for leptoquark masses essentially up to the kinematic limit. Thus, if a leptoquark were discovered, an eγe\gamma collider could play a crucial role in determining its origins.Comment: LaTex file uses aipproc.sty, epsfig, and rotating. 9 pages with 8 postscript figures. Talk given at 20th Annual MRST (Montreal-Rochester-Syracuse-Toronto) Meeting on High-Energy Physics: MRST 98: Toward the Theory of Everything, Montreal, Canada, 13-15 May 199

    Measurement of tan beta in associated t H^\pm Production in gamma gamma Collisions

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    The ratio of neutral Higgs field vacuum expectation values, tan beta, is one of the most important parameters to determine in type-II Two-Higgs Doublet Models (2HDM), specifically the Minimal Supersymmetric Standard Model (MSSM). Assuming the energies and integrated luminosity of a future high energy e^+e^- linear collider of sqrt{s}=500, 800, 1000, and 1500 GeV and L=1 ab^{-1} we show that associated t H^+/- production in gamma gamma collisions can be used to make an accurate determination of tan beta for low and high tan beta by precision measurements of the gamma gamma -> H^+/- t + X cross section.Comment: 7 pages, 11 figures, uses REVTEX

    The validity of capillary blood sampling in the determination of human growth hormone concentration during exercise in men

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    This is an open access article - Copyright © 2004 BMJ Publishing Group LtdBACKGROUND: Studies measuring human growth hormone (hGH) in blood during exercise have mainly used venous sampling. The invasive nature of this procedure makes evaluation of hGH impossible in various exercise environments. OBJECTIVE: To determine whether capillary sampling could offer an alternative sampling method. METHODS: Capillary and venous blood samples were collected for determination of hGH at the end of each exercise stage during an incremental exercise test in 16 male club level competitive cyclists (mean (SD) age 30.8 (8.0) years, body mass 72.2 (7.1) kg, body fat 12.9 (3.5)%, peak oxygen consumption 4.18 (0.46) l⋅min−1). Linear regression, from a plot of venous v capillary blood hGH concentration, showed a correlation coefficient of r = 0.986 (p<0.001). When geometric means and log transformations were used, a coefficient of variation of 14.2% was demonstrated between venous and capillary flow for hGH concentration. The mean ratio limits of agreement were 0.62 (1.72)—that is, 95% of the ratios were contained between 0.36 and 1.07, with a mean of 0.62. CONCLUSIONS: Capillary blood sampling is an acceptable alternative to venous sampling for determining hGH concentration during rest and exercise. Sample sites should not be used interchangeably: one site should be chosen and its use standardised

    Unravelling an Extra Neutral Gauge Boson at the LHC using Third Generation Fermions

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    We study the potential to use measurements of extra neutral gauge bosons (Z') properties in pp collisions at the Large Hadron Collider to unravel the underlying physics. We focus on the usefulness of third generation final states (tau, b, t) in distinguishing between models with non-universal Z'-fermion couplings. We present an update of discovery limits of Z's including the 2010-2011 LHC run and include models with non-universal couplings. We show how ratios of sigma(pp -> Z' -> ttbar), sigma(pp -> Z' -> bbbar), and sigma(pp -> Z' -> tau^+tau^-) to sigma(pp -> Z' -> mu^+mu^-) can be used to distinguish between models and measure parameters of the models. Of specific interest are models with preferential couplings, such as models with generation dependent couplings. We also find that forward-backward asymmetry measurements with third generation fermions in the final state could provide important input to understanding the nature of the Z'. Understanding detector resolution and efficiencies will be crucial for extracting results

    The Aphids (Homoptera: Aphididae) Associated With Bell Peppers and Surrounding Vegetation in Southern Illinois

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    Outbreaks of cucumber mosaic virus (CMV) disease, caused by an aphid- transmitted pathogen, greatly reduced yields of bell pepper in southern Illinois in the mid-1990s. To provide the basis for further studies of the roles of individual apbid species in virus transmission, we surveyed aphid flights in and around pepper fields in 1996 and 1997 by using suction traps, interception nets, landing traps, sweep nets, and hand-picking. We collected 78 species of aphids, 15 of which have been reported to transmit CMV to peppers. The most abundant species taken from suction traps and interception nets in combination were Lipaphis erysimi, Rhopalosiphum padi, Rhopalosiphum maidis, Schizaphis graminum, and Aphis craccivora. All of these species are known to transmit CMV to peppers, but the phenology of R. maidis in Illinois suggests it is not the vector that brings CMV to pepper fields to initiate disease outbreaks. Brachycaudus helichrysi was relatively abundant in 1996 in May and June when a CMV outbreak may have been initiated; it was absent in 1997, and CMV infections were rare that season. Two species, Carolinaia carolinensis and Myzus hemerocallis were recorded for the first time in Illinois
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