1,570 research outputs found

    QCD Phenomenology of Charm Production at HERA

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    We compare different schemes for the treatment of heavy quark production in Deep-Inelastic Scattering (DIS). For fully-integrated quantities such as F2(x,Q2)F_{2}(x,Q^{2}), we advocate the use of the General-Massive Variable-Flavor-Number (GM-VFN) scheme; we present some results showing the progress of a Next-to-Leading Order calculation in this scheme. For differential quantities, the Fixed-Flavor-Number (FFN) scheme provides a more appropriate starting point. We present a new calculation of the azimuthal distribution of charm quark production in DIS. All results have been obtained using a Monte Carlo program under development.Comment: 5 pages, Latex/aipproc, 4 figures, presented at DIS 97, Chicago, IL, April 14-18,199

    Transverse Momentum Distributions in Large-rapidity Dijet Production at the Tevatron

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    In this contribution we examine the transverse momentum distributions in dijet production at large rapidity intervals at the Tevatron, using the BFKL resummation.Comment: 6 pages (1 uu-compressed encapsulated PS figure appended), DESY 94-163, SCIPP 94/2

    Constraints on Little Higgs with Fully-Radiative Electroweak Symmetry Breaking

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    In a recent paper, we introduced a new Little Higgs model, which contains the gauge structure SU(2)3×U(1)SU(2)^3\times U(1), embedded in an approximate global SO(5)×SO(5)SO(5)\times SO(5) symmetry. After breaking to the standard model, SU(2)L×U(1)YSU(2)_L \times U(1)_Y, this produces two heavy Z′Z^\prime bosons and two heavy W′±W^{\prime\pm} bosons, along with a single Standard Model-like Higgs scalar. The unique feature of the model was that it was possible to obtain electroweak symmetry breaking and a light Higgs mass entirely from perturbative loop contributions to the Higgs effective potential. In this paper we consider the electroweak constraints on this model, including tree and loop contributions to the universal oblique and non-oblique parameters, tree-level corrections to the ZWWZWW vertex, and tree and loop level corrections to ZbbˉZb\bar{b}. The most significant corrections are positive tree-level corrections to S^\hat{S} and negative fermion-loop corrections to T^\hat{T}, which require that the scale for the global symmetry breaking be ≳2\gtrsim2 TeV, depending on the top-quark mixing parameter and the extra gauge couplings. In addition, the loop corrections to ZbbˉZb\bar{b} contain a divergence that must be absorbed into the coefficient of a new operator in the theory. The finite part of this ZbbˉZb\bar{b} correction, however, is negligible.Comment: 28 pages, 16 figures, RevTeX forma

    The Infrared Behavior of One-Loop Gluon Amplitudes at Next-to-Next-to-Leading Order

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    For the case of nn-jet production at next-to-next-to-leading order in the QCD coupling, in the infrared divergent corners of phase space where particles are collinear or soft, one must evaluate (n+1)(n+1)-parton final-state one-loop amplitudes through \Ord(\eps^2), where \eps is the dimensional regularization parameter. For the case of gluons, we present to all orders in \eps the required universal functions which describe the behavior of one-loop amplitudes in the soft and collinear regions of phase space. An explicit example is discussed for three-parton production in multi-Regge kinematics that has applications to the next-to-leading logarithmic corrections to the BFKL equation.Comment: Latex, 14 pages, no figure

    Update and review of the multidisciplinary management of stage IV colorectal cancer with liver metastases

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    <p>Abstract</p> <p>Background</p> <p>The management of stage IV colorectal cancer with liver metastases has historically involved a multidisciplinary approach. In the last several decades, there have been great strides made in the therapeutic options available to treat these patients with advancements in medical, surgical, locoregional and adjunctive therapies available to patients with colorectal liver metastases(CLM). As a result, there have been improvements in patient care and survival. Naturally, the management of CLM has become increasingly complex in coordinating the various aspects of care in order to optimize patient outcomes.</p> <p>Review</p> <p>A review of historical and up to date literature was undertaken utilizing Medline/PubMed to examine relevant topics of interest in patients with CLM including criterion for resectability, technical/surgical considerations, chemotherapy, adjunctive and locoregional therapies. This review explores the various disciplines and modalities to provide current perspectives on the various options of care for patients with CLM.</p> <p>Conclusion</p> <p>Improvements in modern day chemotherapy as allowed clinicians to pursue a more aggressive surgical approach in the management of stage IV colorectal cancer with CLM. Additionally, locoregional and adjunctive therapies has expanded the armamentarium of treatment options available. As a result, the management of patients with CLM requires a comprehensive, multidisciplinary approach utilizing various modalities and a more aggressive approach may now be pursued in patients with stage IV colorectal cancer with CLM to achieve optimal outcomes.</p

    Gallus GBrowse: a unified genomic database for the chicken

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    Gallus GBrowse (http://birdbase.net/cgi-bin/gbrowse/gallus/) provides online access to genomic and other information about the chicken, Gallus gallus. The information provided by this resource includes predicted genes and Gene Ontology (GO) terms, links to Gallus In Situ Hybridization Analysis (GEISHA), Unigene and Reactome, the genomic positions of chicken genetic markers, SNPs and microarray probes, and mappings from turkey, condor and zebra finch DNA and EST sequences to the chicken genome. We also provide a BLAT server (http://birdbase.net/cgi-bin/webBlat) for matching user-provided sequences to the chicken genome. These tools make the Gallus GBrowse server a valuable resource for researchers seeking genomic information regarding the chicken and other avian species
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