4,804 research outputs found
Parton Distributions
I discuss our current understanding of parton distributions. I begin with the
underlying theoretical framework, and the way in which different data sets
constrain different partons, highlighting recent developments. The methods of
examining the uncertainties on the distributions and those physical quantities
dependent on them is analysed. Finally I look at the evidence that additional
theoretical corrections beyond NLO perturbative QCD may be necessary, what type
of corrections are indicated and the impact these may have on the
uncertainties.Comment: Invited talk at "XXI International Symposium on Lepton and Photon
Interactions at High Energies," (Fermilab, Chicago, August 2003). 12 pages,
21 figure
Recent Progress in Parton Distributions and Implications for LHC Physics
I outline some of the most recent developments on the global fit to parton
distributions performed by the MRST collaboration.Comment: 6 pages, 7 figures. To appear in proceedings of XIII International
Workshop on Deep Inelastic Scattering, April,27 - May,1, 2005, Madison,
Wisconsin, US
Nonaxisymmetric instability of rapidly rotating black hole in five dimensions
We present results from numerical solution of Einstein's equation in five
dimensions describing evolution of rapidly rotating black holes. We show, for
the first time, that the rapidly rotating black holes in higher dimensions are
unstable against nonaxisymmetric deformation; for the five-dimensional case,
the critical value of spin parameter for onset of the instability is .Comment: 4 pages, 3 figures, accepted for publication in PRD(R
Complex Wave Numbers in the Vicinity of the Schwarzschild Event Horizon
This paper is devoted to investigate the cold plasma wave properties outside
the event horizon of the Schwarzschild planar analogue. The dispersion
relations are obtained from the corresponding Fourier analyzed equations for
non-rotating and rotating, non-magnetized and magnetized backgrounds. These
dispersion relations provide complex wave numbers. The wave numbers are shown
in graphs to discuss the nature and behavior of waves and the properties of
plasma lying in the vicinity of the Schwarzschild event horizon.Comment: 21 pages, 9 figures, accepted for publication Int. J. Mod. Phys.
Classical stability and quantum instability of black-hole Cauchy horizons
For a certain region of the parameter space , the Cauchy
horizon of a (charged) black hole residing in de Sitter space is classically
stable to gravitational perturbations. This implies that, when left to its own
devices, classical theory is unable to retain full predictive power: the
evolution of physical fields beyond the Cauchy horizon is not uniquely
determined by the initial conditions. In this paper we argue that the Cauchy
horizon of a Reissner-Nordstr\"om-de Sitter black hole must always be unstable
quantum mechanically.Comment: 4 pages; uses ReVTeX; figure available upon request to
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