22,402 research outputs found

    Compact QED under scrutiny: it's first order

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    We report new results from our finite size scaling analysis of 4d compact pure U(1) gauge theory with Wilson action. Investigating several cumulants of the plaquette energy within the Borgs-Kotecky finite size scaling scheme we find strong evidence for a first-order phase transition and present a high precision value for the critical coupling in the thermodynamic limit.Comment: Lattice2002(Spin

    Comment on "c-axis Josephson tunneling in Dx2−y2D_{x^2-y^2}-wave superconductors''

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    This comment points out that the recent paper by Maki and Haas [Phys. Rev. B {\bf 67}, 020510 (2003)] is completely wrong.Comment: 1 page, submittted to Phys. Rev.

    A Time-Orbiting Potential Trap for Bose-Einstein Condensate Interferometry

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    We describe a novel atom trap for Bose-Einstein condensates of 87Rb to be used in atom interferometry experiments. The trap is based on a time-orbiting potential waveguide. It supports the atoms against gravity while providing weak confinement to minimize interaction effects. We observe harmonic oscillation frequencies omega_x, omega_y, omega_z as low as 2 pi times (6.0,1.2,3.3) Hz. Up to 2 times 10^4 condensate atoms have been loaded into the trap, at estimated temperatures as low as 850 pK. We anticipate that interferometer measurement times of 1 s or more should be achievable in this device.Comment: 9 pages, 3 figure

    Evolutionary dynamics on strongly correlated fitness landscapes

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    We study the evolutionary dynamics of a maladapted population of self-replicating sequences on strongly correlated fitness landscapes. Each sequence is assumed to be composed of blocks of equal length and its fitness is given by a linear combination of four independent block fitnesses. A mutation affects the fitness contribution of a single block leaving the other blocks unchanged and hence inducing correlations between the parent and mutant fitness. On such strongly correlated fitness landscapes, we calculate the dynamical properties like the number of jumps in the most populated sequence and the temporal distribution of the last jump which is shown to exhibit a inverse square dependence as in evolution on uncorrelated fitness landscapes. We also obtain exact results for the distribution of records and extremes for correlated random variables

    Covariant derivative expansion of Yang-Mills effective action at high temperatures

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    Integrating out fast varying quantum fluctuations about Yang--Mills fields A_i and A_4, we arrive at the effective action for those fields at high temperatures. Assuming that the fields A_i and A_4 are slowly varying but that the amplitude of A_4 is arbitrary, we find a non-trivial effective gauge invariant action both in the electric and magnetic sectors. Our results can be used for studying correlation functions at high temperatures beyond the dimensional reduction approximation, as well as for estimating quantum weights of classical static configurations such as dyons.Comment: Minor changes. References added. Paper accepted for publication in Phys.Rev.

    Investigation of double beta decay with the NEMO-3 detector

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    The double beta decay experiment NEMO~3 has been taking data since February 2003. The aim of this experiment is to search for neutrinoless (0νββ0\nu\beta\beta) decay and investigate two neutrino double beta decay in seven different isotopically enriched samples (100^{100}Mo, 82^{82}Se, 48^{48}Ca, 96^{96}Zr, 116^{116}Cd, 130^{130}Te and 150^{150}Nd). After analysis of the data corresponding to 3.75 y, no evidence for 0νββ0\nu\beta\beta decay in the 100^{100}Mo and 82^{82}Se samples was found. The half-life limits at the 90% C.L. are 1.1⋅10241.1\cdot 10^{24} y and 3.6⋅10233.6\cdot 10^{23} y, respectively. Additionally for 0νββ0\nu\beta\beta decay the following limits at the 90% C.L. were obtained, >1.3⋅1022> 1.3 \cdot 10^{22} y for 48^{48}Ca, >9.2⋅1021> 9.2 \cdot 10^{21} y for 96^{96}Zr and >1.8⋅1022> 1.8 \cdot 10^{22} y for 150^{150}Nd. The 2νββ2\nu\beta\beta decay half-life values were precisely measured for all investigated isotopes.Comment: 12 pages, 4 figures, 5 tables; talk at conference on "Fundamental Interactions Physics" (ITEP, Moscow, November 23-27, 2009

    On viscous flow and azimuthal anisotropy of quark-gluon plasma in strong magnetic field

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    We calculate the viscous pressure tensor of the quark-gluon plasma in strong magnetic field. It is azimuthally anisotropic and is characterized by five shear viscosity coefficients, four of which vanish when the field strength eB is much larger than the plasma temperature squared. We argue, that the azimuthally anisotropic viscous pressure tensor generates the transverse flow with asymmetry as large as 1/3, even not taking into account the collision geometry. We conclude, that the magnitude of the shear viscosity extracted from the experimental data ignoring the magnetic field must be underestimated.Comment: 10 page
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