238 research outputs found

    On Forward J/\psi Production at Fermilab Tevatron

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    The D0 Collaboration has recently reported the measurement of J/\psi production at low angle. We show here that the inclusion of color octet contributions in any framework is able to reproduce this data.Comment: 1 page, Revtex, uses epsfig.sty, 2 postscript figure

    Soft Color Enhancement of the Production of J/psi's by Neutrinos

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    We calculate the production of J/psi mesons by neutrino-nucleon collisions in fixed target experiments. Soft color, often referred to as color evaporation effects, enhance production cross sections due to the contribution of color octet states. Though still small, J/\psi production may be observable in present and future experiments like NuTeV and muon colliders.Comment: 7 pages, Revtex, 4 postscript figures, uses epsfig.st

    Second language user support

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    Computer users rarely experience entirely trouble-free interaction. The natural variety ofindividuals ensures that no software systems yield constantly fluent interaction for allusers. In consequence, software designers often strive to ameliorate this situation bybuilding 'user support' into their systems. User support can take different forms but,conventionally, each aims to assist the needy end-user by means of facilities directly supporting the performance of certain operations, or through supply of information thatadvises the user on available system functionality.The present paper briefly characterises a range of user support facilities before describingone requirement in greater detail. This aspect considers the needs of users whose mother-tongue is not English, but who are obliged to use English-based information systems. Inthis context, 'helping the user' must reasonably extend beyond mere advice on systemoperation to selective elucidation of information content. We regard this move as alogical extension of the user support concept, by seeking to address specific interactionneeds in a target user population. An example of this approach is described through aninformation system, in the domain of civil engineering, for native Chinese speakers ofEnglish

    Diffractive Dissociation In The Interacting Gluon Model

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    We have extended the Interacting Gluon Model (IGM) to calculate diffractive mass spectra generated in hadronic collisions. We show that it is possible to treat both diffractive and non-diffractive events on the same footing, in terms of gluon-gluon collisions. A systematic analysis of available data is performed. The energy dependence of diffractive mass spectra is addressed. They show a moderate narrowing at increasing energies. Predictions for LHC energies are presented.Comment: 12 pages, latex, 14 figures (PostScript Files included); accepted for publication in Phys. Rev. D (Feb.97

    Testing Color Evaporation in Photon-Photon Production of J/Psi at CERN LEP II

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    The DELPHI Collaboration has recently reported the measurement of J/Psi production in photon-photon collisions at LEP II. These newly available data provide an additional proof of the importance of colored c bar{c} pairs for the production of charmonium because these data can only be explained by considering resolved photon processes. We show here that the inclusion of color octet contributions to the J/Psi production in the framework of the color evaporation model is able to reproduce this data. In particular, the transverse-momentum distribution of the J/Psi mesons is well described by this model.Comment: 10 pages, 5 Figures, Revtex

    The Economic Resource Receipt of New Mothers

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    U.S. federal policies do not provide a universal social safety net of economic support for women during pregnancy or the immediate postpartum period but assume that employment and/or marriage will protect families from poverty. Yet even mothers with considerable human and marital capital may experience disruptions in employment, earnings, and family socioeconomic status postbirth. We use the National Survey of Families and Households to examine the economic resources that mothers with children ages 2 and younger receive postbirth, including employment, spouses, extended family and social network support, and public assistance. Results show that many new mothers receive resources postbirth. Marriage or postbirth employment does not protect new mothers and their families from poverty, but education, race, and the receipt of economic supports from social networks do

    Heavy-Flavour Production at HERA

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    We review the theoretical and experimental status of heavy-flavour production at HERA. The results presented include some outstanding issues in charm and beauty photoproduction, charm production in DIS and quarkonium production.Comment: LaTeX, 21 pages, 13 Postscript figures. Summary of the working group on `Heavy Flavour Physics' at the 3rd UK Phenomenology Workshop on HERA Physics, Durham, UK, 20 -- 25 September 1998. To appear in the proceeding

    On the phenomenological analyses of ss-sˉ{\bar s} asymmetry in the nucleon sea

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    Two phenomenological models which give opposite predictions for the ss-sˉ{\bar s} asymmetry in the nucleon sea are re-analyzed carefully. It is pointed out that although the quantitative results in both models depend dramatically on the parameters, the predictions for the shape of s(x)sˉ(x)s(x)-{\bar s}(x) in the two models are parameter independent and opposite. Thereby the coming experiments are likely to be able to distinguish the two models. We find that the reason for the two models giving opposite predictions is that the fluctuation functions and parametrizations for the strange (anti-strange) quark distribution in the baryon (meson) in the two models are quite different. To further investigate these models, we use the same parametrizations for the strange (anti-strange) distributions of the baryon (meson) in the two models. We find that one of the models depends strongly on the parameter which controls the behavior of the meson-baryon fluctuation function. Also the two models agree on the shape and size of ss-sˉ{\bar s} for some values of the model parameters, but can disagree strongly for others.Comment: RevTex, 11 pages, 7 Postscript figure
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