156 research outputs found

    Resumming the color-octet contribution to e+ e- -> J/psi + X

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    Recent observations of the spectrum of J/psi produced in e+ e- collisions at the Upsilon(4S) resonance are in conflict with fixed-order calculations using the Non-Relativistic QCD (NRQCD) effective field theory. One problem is that leading order color-octet mechanisms predict an enhancement of the cross section for J/psi with maximal energy that is not observed in the data. However, in this region of phase space large perturbative corrections (Sudakov logarithms) as well as enhanced nonperturbative effects are important. In this paper we use the newly developed Soft-Collinear Effective Theory (SCET) to systematically include these effects. We find that these corrections significantly broaden the color-octet contribution to the J/psi spectrum. Our calculation employs a one-stage renormalization group evolution rather than the two-stage evolution used in previous SCET calculations. We give a simple argument for why the two methods yield identical results to lowest order in the SCET power counting.Comment: 27 pages, 7 figure

    Power counting and effective field theory for charmonium

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    We hypothesize that the correct power counting for charmonia is in the parameter Lambda_QCD/m_c, but is not based purely on dimensional analysis (as is HQET). This power counting leads to predictions which differ from those resulting from the usual velocity power counting rules of NRQCD. In particular, we show that while Lambda_QCD/m_c power counting preserves the empirically verified predictions of spin symmetry in decays, it also leads to new predictions which include: A hierarchy between spin singlet and triplet octet matrix elements in the J/psi system. A quenching of the net polarization in production at large transverse momentum. No end point enhancement in radiative decays. We discuss explicit tests which can differentiate between the traditional and new theories of NRQCD.Comment: 18 pages, 1 figure Replaced plot of the psi polarization parameter alpha as a function of transverse momentum. Alpha is now closer to zero for large transverse moment

    Hadronic ψ\psi production calculated in the NRQCD factorization formalism

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    The NRQCD factorization formalism of Bodwin, Braaten, and Lepage prescribes how to write quarkonium production rates as a sum of products of short-distance coefficients times non-perturbative long-distance NRQCD matrix elements. We present, in the true spirit of the factorization formalism, a detailed calculation of the inclusive cross section for hadronic ψ\psi production. We find that in addition to the well known {\it color-singlet} production mechanisms, there are equally important mechanisms in which the ccˉc\bar{c} pair that forms the ψ\psi is initially produced in a {\it color-octet} state, in either a 3S1{}^3S_1, 1S0{}^1S_0, 3P0{}^3P_0 or 3P2{}^3P_2 angular-momentum configuration. In our presentation, we emphasize the ``matching'' procedure, which %is the method that allows us to determine the short-distance coefficients appearing in the factorization formula. We also point out how one may systematically include relativistic corrections in these calculations.Comment: 25 pages, 3 postscript figures, use Revtex and epsfig.sty We fixed some typos, added some text regarding a reference, and changed some equations. The file will be available at http://phenom.physics.wisc.edu

    Charmonium production at neutrino factories

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    At existing and planned neutrino factories (high energy and high intensity neutrino beam facilities) precision studies of QCD in neutrino-nucleon interactions are a realistic opportunity. We investigate charmonium production in fixed target neutrino experiments. We find that J/ψJ/\psi production in neutrino-nucleon collision is dominated by the color octet 3S1^3S_1 NRQCD matrix element in a neutral current process, which is not accessible in photo or leptoproduction. Neutrino experiments at a future Muon Collider will acquire sufficient event rate to accurately measure color octet matrix element contributions. The currently running high energy neutrino experiments, NOMAD and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in the figures, otherwise unchange

    Inclusive SS-wave charmonium productions in BB decays

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    The inclusive SS-wave charmonium production rates in BB decays are considered using the Bodwin-Braaten-Lepage (BBL) approach, including the relativistic corrections and the color-octet mechanism suggested as a possible solution to the ψ\psi^{'} puzzle at the Tevatron. We first consider relativistic and radiative corrections to J/ψe+eJ/\psi \rightarrow e^{+} e^{-} and J/ψJ/\psi \rightarrow Light Hadrons (LH), in order to determine two nonperturbative parameters, J/ψO1(3S1)J/ψ\langle J/\psi | O_{1} (^{3}S_{1}) | J/\psi \rangle, J/ψP1(3S1)J/ψ\langle J/\psi | P_{1} (^{3}S_{1}) | J/\psi \rangle, in the factorization formulae for these decays. Using these two matrix elements and including the color-octet ccˉ(3S1)c\bar{c}(^{3}S_{1}) state contribution, we get a moderate increase in the decay rates for BB decays into J/ψ (or ψ) +XJ/\psi ~({\rm or}~\psi^{'}) ~+ X. Our results, B(BJ/ψ (or ψ)+X)=0.58 (0.23)%B(B \rightarrow J/\psi~({\rm or}~\psi^{'}) + X) = 0.58~(0.23) \% for Mb=5.3M_{b} = 5.3 GeV, get closer to the recent CLEO data. As a byproduct, we prefer a larger decay rate for ηc\eta_{c} \rightarrow LH compared to the present data.Comment: 12 page

    Fragmentation Functions for Lepton Pairs

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    We calculate the fragmentation function for a light quark to decay into a lepton pair to leading order in the QCD coupling constant. In the formal definition of the fragmentation function, a QED phase must be included in the eikonal factor to guarantee QED gauge invariance. We find that the longitudinal polarization fraction is a decreasing function of the factorization scale, in accord with the intuitive expectation that the virtual photon should behave more and more like a real photon as the transverse momomentum of the fragmenting quark increases.Comment: 13 pages, 4 figures, normalization corrected, text abbreviate

    The complete chloroplast genome of pearl millet (Pennisetum glaucum (L.) R. Br.) and comparative analysis within the family poaceae

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    The complete chloroplast (cp) genome sequence of Pearl millet (Pennisetum glaucum [L.] R. Br.), an important grain and forage crop in the family Poaceae, is reported in this study. The complete cp genome sequence of P. glaucum is 138,172 bp in length with 38.6% overall GC content and exhibits a typical quadripartite structure comprising one pair of inverted repeat (IR) regions (22,275 bp) separated by a small single-copy (SSC) region (12,409 bp) and a large single-copy (LSC) region (81,213). The P. glaucum cp genome encodes 110 unique genes, 76 of which are protein-coding genes, 4 ribosomal RNA (rRNA) genes, 30 transfer RNA (tRNA) genes and 18 duplicated genes in the IR region. Nine genes contain one or two introns. Whole genome alignments of cp genome were performed for genome-wide comparison. Locally collinear blocks (LCBs) identified among the cp genomes showed that they were well conserved with respect to gene organization and order. This newly determined cp genome sequence of P. glaucum will provide valuable information for the future breeding programs of valuable cereal crops in the family Poaceae

    Noncommutative brane-world, (Anti) de Sitter vacua and extra dimensions

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    We investigate a curved brane-world, inspired by a noncommutative D3-brane, in a type IIB string theory. We obtain, an axially symmetric and a spherically symmetric, (anti) de Sitter black holes in 4D. The event horizons of these black holes possess a constant curvature and may be seen to be governed by different topologies. The extremal geometries are explored, using the noncommutative scaling in the theory, to reassure the attractor behavior at the black hole event horizon. The emerging two dimensional, semi-classical, black hole is analyzed to provide evidence for the extra dimensions in a curved brane-world. It is argued that the gauge nonlinearity in the theory may be redefined by a potential in a moduli space. As a result, D=11 and D=12 dimensional geometries may be obtained at the stable extrema of the potential.Comment: 17 pages, 1 figur

    Thermodynamic and gravitational instability on hyperbolic spaces

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    We study the properties of anti--de Sitter black holes with a Gauss-Bonnet term for various horizon topologies (k=0, \pm 1) and for various dimensions, with emphasis on the less well understood k=-1 solution. We find that the zero temperature (and zero energy density) extremal states are the local minima of the energy for AdS black holes with hyperbolic event horizons. The hyperbolic AdS black hole may be stable thermodynamically if the background is defined by an extremal solution and the extremal entropy is non-negative. We also investigate the gravitational stability of AdS spacetimes of dimensions D>4 against linear perturbations and find that the extremal states are still the local minima of the energy. For a spherically symmetric AdS black hole solution, the gravitational potential is positive and bounded, with or without the Gauss-Bonnet type corrections, while, when k=-1, a small Gauss-Bonnet coupling, namely, \alpha << {l}^2 (where l is the curvature radius of AdS space), is found useful to keep the potential bounded from below, as required for stability of the extremal background.Comment: Shortened to match published (PRD) version, 18 pages, several eps figure

    Understanding museum vacationers’ eco-friendly decision-making process: Strengthening the VBN framework

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    In the present research, the process of vacationers’ pro-environmental decision formation for environmentally responsible museums was examined. This research employed and broadened the value-belief-norm theory, using satisfaction with green product use, green trust, and frequency of past behavior for green product use as predictors. A structural equation modeling was utilized for modeling comparisons and hypothesis testing. A measurement model tested using the data gathered at museums was found to satisfactorily fit to the data. Newly integrated constructs significantly improved the prediction power of the theory. In addition, results of the structural equation modeling generally supported the proposed relationships. Moreover, a salient role of moral norm was identified. As expected, new environmental paradigm, awareness of consequences, ascribed responsibility, and moral norm played an important mediating role. A parsimonious model with greater prediction power than the original value-belief-norm theory was produced through modeling comparisons and the process of testing relationships among research variables. Our results offer a sufficient understanding of vacationers’ pro-environmental intention for eco-friendly museums
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