1,018 research outputs found

    QGP collective effects and jet transport

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    We present numerical simulations of the SU(2) Boltzmann-Vlasov equation including both hard elastic particle collisions and soft interactions mediated by classical Yang-Mills fields. We provide an estimate of the coupling of jets to a hot isotropic plasma, which is independent of infrared cutoffs. In addition, we investigate jet propagation in anisotropic plasmas, as created in heavy-ion collisions. The broadening of jets is found to be stronger along the beam line than in azimuth due to the creation of field configurations with B_t>E_t and E_z>B_z via plasma instabilities.Comment: 4 pages, 5 figures. Presented at the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008), Jaipur, India, 4-10 Feb 200

    How Wide is the Transition to Deconfinement?

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    Pure SU(3) glue theories exhibit a deconfining phase transition at a nonzero temperature, Tc. Using lattice measurements of the pressure, we develop a simple matrix model to describe the transition region, when T > Tc. This model, which involves three parameters, is used to compute the behavior of the 't Hooft loop. There is a Higgs phase in this region, where off diagonal color modes are heavy, and diagonal modes are light. Lattice measurements of the latter suggests that the transition region is narrow, extending only to about 1.2 Tc. This is in stark contrast to lattice measurements of the renormalized Polyakov loop, which indicates a much wider width. The possible implications for the differences in heavy ion collisions between RHIC and the LHC are discussed.Comment: v2: Minor changes in wording, references adde

    A Weibel Instability in the Melting Color Glass Condensate

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    Based on hep-ph/0510121, we discuss further the numerical study of classical SU(2) 3+1-D Yang-Mills equations for matter produced in a high energy heavy ion collision. The growth of the amplitude of fluctuations as exp(Γg2μτ)\exp{(\Gamma \sqrt{g^2\mu \tau})} (where g2μg^2\mu is a scale arising from the saturation of gluons in the nuclear wavefunction) is shown to be robust over a wide range of initial amplitudes that violate boost invariance. We argue that this growth is due to a non-Abelian Weibel instability, the scale of which is set by a dynamically generated plasmon mass. We find good agreement when we relate Γ\Gamma to the prediction from kinetic theory.Comment: 8 pages, invited talk at Workshop on Quark Gluon Plasma Thermalization, Vienna, August 10th-12th, 200

    A survey on fuzzy fractional differential and optimal control nonlocal evolution equations

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    We survey some representative results on fuzzy fractional differential equations, controllability, approximate controllability, optimal control, and optimal feedback control for several different kinds of fractional evolution equations. Optimality and relaxation of multiple control problems, described by nonlinear fractional differential equations with nonlocal control conditions in Banach spaces, are considered.Comment: This is a preprint of a paper whose final and definite form is with 'Journal of Computational and Applied Mathematics', ISSN: 0377-0427. Submitted 17-July-2017; Revised 18-Sept-2017; Accepted for publication 20-Sept-2017. arXiv admin note: text overlap with arXiv:1504.0515

    Two-point functions for SU(3) Polyakov Loops near T_c

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    We discuss the behavior of two point functions for Polyakov loops in a SU(3) gauge theory about the critical temperature, T_c. From a Z(3) model, in mean field theory we obtain a prediction for the ratio of masses at T_c, extracted from correlation functions for the imaginary and real parts of the Polyakov loop. This ratio is m_i/m_r = 3 if the potential only includes terms up to quartic order in the Polyakov loop; its value changes as pentic and hexatic interactions become important. The Polyakov Loop Model then predicts how m_i/m_r changes above T_c.Comment: 5 pages, no figures; reference adde

    A user-centric execution environment for <em>CineGrid</em> workloads

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    The abundance and heterogeneity of IT resources available, together with the ability to dynamically scale applications poses significant usability issues to users. Without understanding the performance profile of available resources users are unable to efficiently scale their applications in order to meet performance objectives. High quality media collaborations, like CineGrid, are one example of such diverse environments where users can leverage dynamic infrastructures to move and process large amounts of data. This paper describes our user-centric approach to executing high quality media processing workloads over dynamic infrastructures. Our main contribution is the CGtoolkit environment, an integrated system which aids users cope with the infrastructure complexity and large data sets specific to the digital cinema domain

    Asymptotic integration of (1+α)(1+\alpha)-order fractional differential equations

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    \noindent{\bf Abstract} We establish the long-time asymptotic formula of solutions to the (1+α)(1+\alpha)--order fractional differential equation 0iOt1+αx+a(t)x=0{}_{0}^{\>i}{\cal O}_{t}^{1+\alpha}x+a(t)x=0, t>0t>0, under some simple restrictions on the functional coefficient a(t)a(t), where 0iOt1+α{}_{0}^{\>i}{\cal O}_{t}^{1+\alpha} is one of the fractional differential operators 0Dtα(x){}_{0}D_{t}^{\alpha}(x^{\prime}), (0Dtαx)=0Dt1+αx({}_{0}D_{t}^{\alpha}x)^{\prime}={}_{0}D_{t}^{1+\alpha}x and 0Dtα(txx){}_{0}D_{t}^{\alpha}(tx^{\prime}-x). Here, 0Dtα{}_{0}D_{t}^{\alpha} designates the Riemann-Liouville derivative of order α(0,1)\alpha\in(0,1). The asymptotic formula reads as [a+O(1)]xsmall+bxlarge[a+O(1)]\cdot x_{{\scriptstyle small}}+b\cdot x_{{\scriptstyle large}} as t+t\rightarrow+\infty for given aa, bRb\in\mathbb{R}, where xsmallx_{{\scriptstyle small}} and xlargex_{{\scriptstyle large}} represent the eventually small and eventually large solutions that generate the solution space of the fractional differential equation 0iOt1+αx=0{}_{0}^{\>i}{\cal O}_{t}^{1+\alpha}x=0, t>0t>0.Comment: 16 page
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