430 research outputs found

    Energy Conservation Constraints on Multiplicity Correlations in QCD Jets

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    We compute analytically the effects of energy conservation on the self-similar structure of parton correlations in QCD jets. The calculations are performed both in the constant and running coupling cases. It is shown that the corrections are phenomenologically sizeable. On a theoretical ground, energy conservation constraints preserve the scaling properties of correlations in QCD jets beyond the leading log approximation.Comment: 11 pages, latex, 5 figures, .tar.gz version avaliable on ftp://www.inln.unice.fr

    Generalised Factorial Moments and QCD Jets

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    { In this paper we present a natural and comprehensive generalisation of the standard factorial moments (\clFq) analysis of a multiplicity distribution. The Generalised Factorial Moments are defined for all qq in the complex plane and, as far as the negative part of its spectrum is concerned, could be useful for the study of infrared structure of the Strong Interactions Theory of high energy interactions (LEP multiplicity distribution under the Z0{\cal Z}_0). The QCD calculation of the Generalised Factorial Moments for negative qq is performed in the double leading log accuracy and is compared to OPAL experimental data. The role played by the infrared cut-off of the model is discussed and illustrated with a Monte Carlo calculation. }Comment: 11pages 4 figures uuencode, LATEC, INLN 94/

    Total Cross Section, Inelasticity and Multiplicity Distributions in Proton -- Proton Collisions

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    Multiparticle production in high energy proton -- proton collisions has been analysed in the frame of Strongly Correlated Quark Model (SCQM) of the hadron structure elaborated by the author. It is shown that inelasticity decreases at high energies and this effect together with the total cross section growth and the increasing with collision energy the masses of intermediate clusters result in the violation of KNO -- scaling.Comment: 21 pages, 11 figures, submitted to Yad. Fisik

    Comportamento fenologico e produtivo das variedades de uva 'Ribol' e 'Superior Seedless' na regiao de Jaboticabal, SP.

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    A introducao de novas variedades de videira e o estudo de seu comportamento e adaptacao nas diferentes regioes produtoras do pais constituem em importante alternativa para oferecer frutos diferenciados e de elevada qualidade aos consumidores, contribuindo para aumentar a lucratividade da atividade viticola. Realizou-se este trabalho com o objetivo de estudar o comportamento agronomico, fenologico e as exigencias termicas das variedades Ribol e Superior Seedless na regiao de Jaboticabal, SP. A variedade Ribol destacou-se com elevada producao/planta, boas caracteristicas de cacho e periodo fenologico de poda a colheita de 150 dias, apresentando-se com potencial para o cultivo na regiao Oeste do estado de Sao Paulo. A variedade Superior Seedless, apesar das boas caracteristicas dos cachos, apresentou produtividade muito baixa, necessitando de maiores estudos para ajuste da tecnologia de producao

    Intermittency in Branching Processes

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    We study the intermittency properties of two branching processes, one with a uniform and another with a singular splitting kernel. The asymptotic intermittency indices, as well as the leading corrections to the asymptotic linear regime are explicitly computed in an analytic framework. Both models are found to possess a monofractal spectrum with φq=q1\varphi_{q}=q-1. Relations with previous results are discussed.Comment: 20 pages, UCLA93/TEP/2

    Search for Neutral Q-balls in Super-Kamiokande II

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    A search for Q-balls induced groups of successive contained events has been carried out in Super-Kamiokande II with 541.7 days of live time. Neutral Q-balls would emit pions when colliding with nuclei, generating a signal of successive contained pion events along a track. No candidate for successive contained event groups has been found in Super-Kamiokande II, so upper limits on the possible flux of such Q-balls have been obtained.Comment: 5 pages, 5 figures, Submitted to Phys. Lett.

    J/Psi Suppression in Heavy Ion Collisions at the CERN SPS

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    We reexamine the production of J/Psi and other charmonium states for a variety of target-projectile choices at the SPS. For this study we use a newly constructed cascade code LUCIFER II, which yields acceptable descriptions of both hard and soft processes, specifically Drell-Yan and hidden charm production, and soft energy loss and meson production, at the SPS. Glauber calculations of other authors are redone, and compared directly to the cascade results. The modeling of the charmonium states differs from that of earlier workers in its unified treatment of the hidden charm meson spectrum, which is introduced from the outset as a set of coupled states. The result is a description of the NA38 and NA50 data in terms of a conventional hadronic picture. The apparently anomalous suppression found in the most massive Pb+Pb system arises from three sources: destruction in the initial nucleon-nucleon cascade, use of coupled channels to exploit the larger breakup in the less bound Chi and Psi' states, and comover interaction in the final low energy phase.Comment: 36 pages (15 figures

    Dynamical Pion Production via Parametric Resonance from Disoriented Chiral Condensate

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    We discuss a dynamical mechanism of pion production from disoriented chiral condensates (DCC). It leads to an explosive production of pions via the parametric amplification mechanism, which is similar to the reheating mechanism in inflationary cosmology. Classically, it is related with the instability in the solutions of the Mathieu equation and we explore the quantum aspects of the mechanism. We show that nonlinearlities and back reactions can be ignorable for sufficiently long time under the small amplitude approximations of background σ\sigma oscillations, which may be appropriate for the late stage of nonequilibrium phase transition. It allows us to obtain an explicit quantum state of the produced pions and σ\sigma, the squeezed state of BCS type. Single particle distributions and two-pion correlation functions are computed within these approximations. The results obtained illuminate the characteristic features of multi-pion states produced through the parametric amplification mechanism. In particular, two-pion correlations of various charge combinations contain back-to-back correlations which cannot be masked by the identical particle interference effect.Comment: REVTEX 18 pages and 10 figure

    Wheat-barley hybridization – the last forty years

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    Abstract Several useful alien gene transfers have been reported from related species into wheat (Triticum aestivum), but very few publications have dealt with the development of wheat/barley (Hordeum vulgare) introgression lines. An overview is given here of wheat 9 barley hybridization over the last forty years, including the development of wheat 9 barley hybrids, and of addition and translocation lines with various barley cultivars. A short summary is also given of the wheat 9 barley hybrids produced with other Hordeum species. The meiotic pairing behaviour of wheat 9 barley hybrids is presented, with special regard to the detection of wheat– barley homoeologous pairing using the molecular cytogenetic technique GISH. The effect of in vitro multiplication on the genome composition of intergeneric hybrids is discussed, and the production and characterization of the latest wheat/barley translocation lines are presented. An overview of the agronomical traits (b-glucan content, earliness, salt tolerance, sprouting resistance, etc.) of the newly developed introgression lines is given. The exploitation and possible use of wheat/barley introgression lines for the most up-to-date molecular genetic studies (transcriptome analysis, sequencing of flow-sorted chromosomes) are also discussed
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