76,632 research outputs found

    Recent BES measurements and the hadronic contribution to the QED vacuum polarization

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    We have updated our evaluation of the hadronic contribution to the running of the QED fine structure constant using the recent precise measurements of the e+e- annihilation at the center-of-mass (c.m.s.) energy region between 2.6 and 3.65 GeV performed by the BES collaboration. In the low energy region, around the rho resonance, we include the recent measurements from the BABAR, CDM-2, KLOE and SND collaborations. We obtain Delta alpha (5)_had (s) = 0.02750 +/- 0.00033 at s = m_Z^2.Comment: 3 pages, 1 figur

    Loss of mass and stability of galaxies in MOND

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    The self-binding energy and stability of a galaxy in MOND-based gravity are curiously decreasing functions of its center of mass acceleration towards neighbouring mass concentrations. A tentative indication of this breaking of the Strong Equivalence Principle in field galaxies is the RAVE-observed escape speed in the Milky Way. Another consequence is that satellites of field galaxies will move on nearly Keplerian orbits at large radii (100 - 500 kpc), with a declining speed below the asymptotically constant naive MOND prediction. But consequences of an environment-sensitive gravity are even more severe in clusters, where member galaxies accelerate fast: no more Dark-Halo-like potential is present to support galaxies, meaning that extended axisymmetric disks of gas and stars are likely unstable. These predicted reappearance of asymptotic Keplerian velocity curves and disappearance of "stereotypic galaxies" in clusters are falsifiable with targeted surveys.Comment: 4 pages, 2 figures, ApJ Letter

    Self-consistent models of triaxial galaxies in MOND gravity

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    The Bekenstein-Milgrom gravity theory with a modified Poisson equation is tested here for the existence of triaxial equilibrium solutions. Using the non-negative least square method, we show that self-consistent triaxial galaxies exist for baryonic models with a mild density cusp ÏâˆŒÎŁr\rho \sim {\Sigma \over r}. Self-consistency is achieved for a wide range of central concentrations, ÎŁâˆŒ10−1000M⊙pc−2\Sigma \sim 10-1000\mathrm{M_{\odot}pc^{-2}}, representing low-to-high surface brightness galaxies. Our results demonstrate for the first time that the orbit superposition technique is fruitful for constructing galaxy models beyond Newtonian gravity, and triaxial cuspy galaxies might exist without the help of Cold dark Matter.Comment: 19 pages, 1 table, 7 figures, Accepted for publication in Ap

    Infinite Hopf family of elliptic algebras and bosonization

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    Elliptic current algebras E_{q,p}(\hat{g}) for arbitrary simply laced finite dimensional Lie algebra g are defined and their co-algebraic structures are studied. It is shown that under the Drinfeld like comultiplications, the algebra E_{q,p}(\hat{g}) is not co-closed for any g. However putting the algebras E_{q,p}(\hat{g}) with different deformation parameters together, we can establish a structure of infinite Hopf family of algebras. The level 1 bosonic realization for the algebra E_{q,p}(\hat{g}) is also established.Comment: LaTeX, 11 pages. This is the new and final versio
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