76,632 research outputs found
Recent BES measurements and the hadronic contribution to the QED vacuum polarization
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
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
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 . Self-consistency is achieved for a wide range of central
concentrations, , 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
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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