21,657 research outputs found

    Magnetic Component of Quark-Gluon Plasma

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    We describe recent developments of the "magnetic scenario" of sQGP. We show that at T=(0.8−1.3)TcT=(0.8-1.3)T_c there is a dense plasma of monopoles, capable of supporting metastable flux tubes. Their existence allows to quantitatively explained the non-trivial TT-dependence of the static QˉQ\bar Q Q potential energy calculated on the lattice. By molecular dynamics simulation we derived transport properties (shear viscosity and diffusion constant) and showed that the best liquid is given by most symmetric plasma, with 50%-50% of electric and magnetic charges. The results are close to those of the ``perfect liquid'' observed at RHIC.Comment: Contribution to the 20th International Conference on Nucleus Nucleus Collisions (Quark Matter 2008

    Interaction of cosmic background neutrinos with matter of periodic structure

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    We study coherent interaction of cosmic background neutrinos(CBNs) with matter of periodic structure. The mixing and small masses of neutrinos discovered in neutrino oscillation experiments indicate that CBNs which have very low energy today should be in mass states and can transform from one mass state to another in interaction with electrons in matter. We show that in a coherent scattering process a periodic matter structure designed to match the scale of the mass square difference of neutrinos can enhance the conversion of CBNs from one mass state to another. Energy of CBNs can be released in this scattering process and momentum transfer from CBNs to electrons in target matter can be obtained.Comment: 6 pages, 5 figures, publication versio

    No UV/IR Mixing in Unitary Space-Time Noncommutative Field Theory

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    In this article we calculate several divergent amplitudes in phi^4-theory on non-commutative space-time in the framework of Interaction Point Time Ordered Perturbation Theory (IPTOPT), continuing work done in hep-th/0209253. On the ground of these results we find corresponding Feynman rules which allow for a much easier diagrammatic calculation of amplitudes. The most important feature of the present theory is the lack of the UV/IR mixing problem in all amplitudes calculated so far. Although we are not yet able to give a rigorous proof, we provide a strong argument for this result to hold in general. Together with the found Feynman rules this opens promising vistas towards the systematic renormalization of non-commutative field theories.Comment: 23 pages, uses package feynmf, v2: typos, added reference, minor improvement

    What do lattice baryonic susceptibilities tell us about quarks, diquarks and baryons at T>TcT>Tc?

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    Lattice data on QCD thermodynamics, especially recent study of high order susceptibilities by UK-Bielefeld collaboration, have provided valuable information about matter properties around and above the critical temperature TcT_c. In this work we tried to understand what physical picture would explain these numerical data. We found two scenarios which will do it: (i) a quark quasiparticle gas, with the effective mass which is strongly decreasingdecreasing near the phase boundary into the QGP phase; or (ii) a picture including baryons at T>TcT>T_c, with the mass rapidly increasingincreasing across the phase boundary toward QGP. We further provide several arguments in favor of the latter scenario, one of which is a natural continuity with the baryon gas picture at T<TcT<T_c.Comment: 11 pages, 7 figures. One reference as well as few comments were adde

    Angular Dependence of Jet Quenching Indicates Its Strong Enhancement Near the QCD Phase Transition

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    We study dependence of jet quenching on matter density, using "tomography" of the fireball provided by RHIC data on azimuthal anisotropy v2v_2 of high ptp_t hadron yield at different centralities. Slicing the fireball into shells with constant (entropy) density, we derive a "layer-wise geometrical limit" v2maxv_2^{max} which is indeed above the data v2<v2maxv_2<v_2^{max}. Interestingly, the limit is reached only if quenching is dominated by shells with the entropy density exactly in the near-TcT_c region. We show two models that simultaneously describe the high ptp_t v2v_2 and RAAR_{AA} data and conclude that such a description can be achieved only if the jet quenching is few times stronger in the near-TcT_c region relative to QGP at T>TcT>T_c. One possible reason for that may be recent indications that the near-TcT_c region is a magnetic plasma of relatively light color-magnetic monopoles.Comment: 4 pages, 4 figures. Final version published as PRL102,202302(2009

    Constraints on Neutrino Velocities Revisited

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    With a minimally modified dispersion relation for neutrinos, we reconsider the constraints on superluminal neutrino velocities from bremsstrahlung effects in the laboratory frame. Employing both the direct calculation approach and the virtual Z-boson approach, we obtain the generic decay width and energy loss rate of a superluminal neutrino with general energy. The Cohen-Glashow's analytical results for neutrinos with a relatively low energy are confirmed in both approaches. We employ the survival probability instead of the terminal energy to assess whether a neutrino with a given energy is observable or not in the OPERA experiment. Moreover, using our general results we perform systematical analyses on the constraints arising from the Super-Kamiokande and IceCube experiments.Comment: RevTex4, 14 pages, 5 figures, minor corrections, version to appear in Phys. Rev.

    Limiting efficiencies of solar energy conversion and photo-detection via internal emission of hot electrons and hot holes in gold

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    We evaluate the limiting efficiency of full and partial solar spectrum harvesting via the process of internal photoemission in Au-semiconductor Schottky junctions. Our results based on the ab initio calculations of the electron density of states (e-DOS) reveal that the limiting efficiency of the full-spectrum Au converter based on hot electron injection is below 4%. This value is even lower than previously established limit based on the parabolic approximation of the Au electron energy bands. However, we predict limiting efficiency exceeding 10% for the hot holes collection through the Schottky junction between Au and p-type semiconductor. Furthermore, we demonstrate that such converters have more potential if used as a part of the hybrid system for harvesting high- and low-energy photons of the solar spectrum.Comment: Proc. SPIE 9608, Infrared Remote Sensing and Instrumentation XXIII, 960816 (September 1, 2015) 7 pages, 4 figure
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