395 research outputs found

    Higgs Production at NNLO

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    We describe the calculation of inclusive Higgs boson production at hadronic colliders at next-to-next-to-leading order (NNLO) in perturbative quantum chromodynamics. We have used the technique developed in reference [4]. Our results agree with those published earlier in the literature.Comment: Talk given at PASCOS'03, TIFR, Mumbai, LaTeX, 5 page

    Helicity Amplitudes for Charmonium Production in Hadron-Hadron and Photon-Hadron Collisions

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    We present the gluon-gluon and photon-gluon helicity amplitudes for color singlet and octet charmonium production in polarized and unpolarized hadron-hadron and photon-hadron collisions.Comment: 11 pages amstex no figure

    Parton Distributions

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    I discuss our current understanding of parton distributions. I begin with the underlying theoretical framework, and the way in which different data sets constrain different partons, highlighting recent developments. The methods of examining the uncertainties on the distributions and those physical quantities dependent on them is analysed. Finally I look at the evidence that additional theoretical corrections beyond NLO perturbative QCD may be necessary, what type of corrections are indicated and the impact these may have on the uncertainties.Comment: Invited talk at "XXI International Symposium on Lepton and Photon Interactions at High Energies," (Fermilab, Chicago, August 2003). 12 pages, 21 figure

    Differential Cross Sections for Higgs Production

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    We review recent theoretical progress in evaluating higher order QCD corrections to Higgs boson differential distributions at hadron-hadron colliders

    Conical square function estimates in UMD Banach spaces and applications to H-infinity functional calculi

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    We study conical square function estimates for Banach-valued functions, and introduce a vector-valued analogue of the Coifman-Meyer-Stein tent spaces. Following recent work of Auscher-McIntosh-Russ, the tent spaces in turn are used to construct a scale of vector-valued Hardy spaces associated with a given bisectorial operator (A) with certain off-diagonal bounds, such that (A) always has a bounded (H^{\infty})-functional calculus on these spaces. This provides a new way of proving functional calculus of (A) on the Bochner spaces (L^p(\R^n;X)) by checking appropriate conical square function estimates, and also a conical analogue of Bourgain's extension of the Littlewood-Paley theory to the UMD-valued context. Even when (X=\C), our approach gives refined (p)-dependent versions of known results.Comment: 28 pages; submitted for publicatio

    Deep-inelastic production of heavy quarks

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    Deep-inelastic production of heavy quarks at HERA, especially charm, is an excellent signal to measure the gluon distribution in the proton at small xx values. By measuring various differential distributions of the heavy quarks this reaction permits additional more incisive QCD analyses due to the many scales present. Furthermore, the relatively small mass of the charm quark, compared to the typical momentum transfer QQ, allows one to study whether and when to treat this quark as a parton. This reaction therefore sheds light on some of the most fundamental aspects of perturbative QCD. We discuss the above issues and review the feasibility of their experimental investigation in the light of a large integrated luminosity.Comment: 10 pages, uses epsfig.sty, five ps figures included. To appear in the proceedings of the workshop Future Physics at HERA, eds. G. Ingelman, A. De Roeck and R. Klanner, DESY, Hamburg, 199

    Stochastic evolution equations driven by Liouville fractional Brownian motion

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    Let H be a Hilbert space and E a Banach space. We set up a theory of stochastic integration of L(H,E)-valued functions with respect to H-cylindrical Liouville fractional Brownian motions (fBm) with arbitrary Hurst parameter in the interval (0,1). For Hurst parameters in (0,1/2) we show that a function F:(0,T)\to L(H,E) is stochastically integrable with respect to an H-cylindrical Liouville fBm if and only if it is stochastically integrable with respect to an H-cylindrical fBm with the same Hurst parameter. As an application we show that second-order parabolic SPDEs on bounded domains in \mathbb{R}^d, driven by space-time noise which is white in space and Liouville fractional in time with Hurst parameter in (d/4,1) admit mild solution which are H\"older continuous both and space.Comment: To appear in Czech. Math.

    Determination of the asymptotic behaviour of the heavy flavour coefficient functions in deep inelastic scattering

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    Using renormalization group techniques we have derived analytic formulae for the next-to-leading order heavy-quark coefficient functions in deep inelastic lepton hadron scattering. These formulae are only valid in the kinematic regime Q^2 >> m^2, where Q^2 and m^2 stand for the masses squared of the virtual photon and heavy quark respectively. Some of the applications of these asymptotic formulae will be discussed.Comment: Latex with two PostScript figures and style file. Presentation at the Rheinsberg Meeting on Higher Order QCD and QE

    Моделювання процесу обробки на фрезерному верстаті 6Р13Ф3 та прогнозування показників процесу стружкоутворення

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    Розроблено методологію побудови раціональної з точки зору витрат ресурсів обчислювальної системи скінчено-елементної сітки складної технологічної системи, що включає елементи різної маси, жорсткості та розмірів, а також рухомі та нерухомі з’єднання зі скінченою величиною контактної жорсткості. Проведені пошукові розрахунки процесу стружкоутворення у абсолютно жорсткій та податливій технологічній системах, результати яких показали, що переміщення у технологічній системі в момент врізання призводять до запізнення початку сталого стружкоутворення, додаткового тертя зубів о заготовку без різання та активації вібрацій. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/2685
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