84,034 research outputs found

    Poincar\'e Supersymmetry Representations Over Trace Class Noncommutative Graded Operator Algebras

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    We show that rigid supersymmetry theories in four dimensions can be extended to give supersymmetric trace (or generalized quantum) dynamics theories, in which the supersymmetry algebra is represented by the generalized Poisson bracket of trace supercharges, constructed from fields that form a trace class noncommutative graded operator algebra. In particular, supersymmetry theories can be turned into supersymmetric matrix models this way. We demonstrate our results by detailed component field calculations for the Wess-Zumino and the supersymmetric Yang-Mills models (the latter with axial gauge fixing), and then show that they are also implied by a simple and general superspace argument.Comment: plaintex, 23 Page

    Studying Jets with Identified Particles in PHENIX

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    A surprising excess of protons at intermediate pTp_T, 2-5GeV/c, has been observed in Au+Au collisions at RHIC, for which the source is not known. In p+p collisions, particles at this pTp_T arise from jet fragmentation, however the observed baryon yield in central Au+Au collisions are not compatible with the usual jet fragmentation function. Two particle Δϕ\Delta\phi correlations are a powerful probe for quantitatively understanding the modifications to jet fragmentation from interactions with the medium. Earlier studies have shown that the excess baryons do have jet-like partners, indicating a hard scattering origin. We present new results from a systematic study of two particle correlations as a function of trigger and partner particle species, charge, pTp_T and centrality from the high statistics Au+Au dataset. p+p collisions are also analyzed as a reference.Comment: 4 pages, 3 figures, talk given at Hard Probes 200

    Electromagnetic Probes in PHENIX

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    Electromagnetic probes are arguably the most universal tools to study the different physics processes in high energy hadron and heavy ion collisions. In this paper we summarize recent measurements of real and virtual direct photons at central rapidity by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au collisions. We also discuss the impact of the results and the constraints they put on theoretical models. At the end we report on the immediate as well as on the mid-term future of photon measurements at RHIC.Comment: 8 pages, 9 postscript figures, to be published in the Proceedings of the Hard Probes 2006 conference (June 9-16, 2006, Asilomar, CA

    Short Distance Behavior of (2+1)-dimensional QCD

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    Within the framework of semiclassical QCD approximations the short distance behavior of two static color charges in (2+1)-dimensional QCD is discussed. A classical linearization of the field equations is exhibited and leads to analytical results producing the static potential. Beyond the dominant classical part proportional to ln lambda R, QCD contributions of order R^1/2 and R are found.Comment: 9 pages, uses LaTeX and elsart.st

    Anomalous \phi Meson Suppression in Au+Au Collisions at \sqrt{s_{NN}}=200 GeV Measured by the PHENIX Experiment at RHIC

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    The PHENIX experiment at RHIC has measured the \phi-meson production at mid-rapidity in p+p, d+Au, Cu+Cu and Au+Au collisions at \sqrt{s_{NN}}=200 GeV via the K^+K^- decay mode. The transverse momentum spectra of the \phi-meson and the nuclear modification factor as a function of centrality are reviewed here.Comment: 4 pages, 4 figures; To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

    Composite leptons and quarks constructed as triply occupied quasiparticles in quaternionic quanutm mechanics

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    \noindent We propose a set of rules for constructing composite leptons and quarks as triply occupied quasiparticles, in the quaternionic quantum mechanics of a pair of Harari-Shupe preons TT and VV. The composites fall into two classes, those with totally antisymmetric internal wave functions, and those with internal wave functions of mixed symmetry. The mixed symmetry states consist of precisely the three spin 1/2 quark lepton families used in the standard model (48 particle states, {\it not} counting the doubling arising from antiparticles), plus one doublet of spin 3/2 quarks (24 particle states). The antisymmetric states consist of a set of spin 3/2 leptonic states with charges as in a standard model family (16 particle states), and a spin 1/2 leptonic fractionally charged doublet (4 particle states). We sketch ideas for deriving our rules from a fundamental quaternionic preonic field theory.Comment: 10pages,plain tex, IASSNS-HEP-94/2

    Jet properties from di-hadron correlations in p+p collisions at s**(1/2) = 200-GeV

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    An analysis of high pT hadron spectra associated with high pT π0\pi^0 particles in p+p collisions at s**(1/2) = 200-GeV is presented. The shape of the azimuthal angular correlation is used to determine the value of partonic intrinsic momentum \sqrt{\left} = 2.68 \pm 0.07(\rm stat) \pm 0.34(\rm sys) GeV/c. The effect of kT-smearing of inclusive π0\pi^0 cross section is discussed.Comment: To appear in the proceedings of 2nd International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2006), Asilomar, Pacific Grove, California, 9-16 Jun 200

    Nowhere dense graph classes, stability, and the independence property

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    A class of graphs is nowhere dense if for every integer r there is a finite upper bound on the size of cliques that occur as (topological) r-minors. We observe that this tameness notion from algorithmic graph theory is essentially the earlier stability theoretic notion of superflatness. For subgraph-closed classes of graphs we prove equivalence to stability and to not having the independence property.Comment: 9 page

    Probing High Parton Densities at Low-xx in d+Au Collisions at PHENIX Using the New Forward and Backward Muon Piston Calorimeters

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    The new forward Muon Piston Calorimeters allow PHENIX to explore low-xx parton distributions in d+Au collisions with hopes of observing gluon saturation. We present a two-particle azimuthal Δϕ\Delta \phi correlation measurement made between a mid-rapidity particle (η1<0.35|\eta_1| < 0.35) and a forward π0\pi^0 (3.1<η2<3.93.1 < \eta_2 < 3.9) wherein we compare correlation widths in d+Au to p+p and compute IdAI_{dA}.Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse