12,991 research outputs found
Higher-Dimensional Bulk Wormholes and their Manifestations in Brane Worlds
There is nothing to prevent a higher-dimensional anti-de Sitter bulk
spacetime from containing various other branes in addition to hosting our
universe, presumed to be a positive-tension 3-brane. In particular, it could
contain closed, microscopic branes that form the boundary surfaces of void
bubbles and thus violate the null energy condition in the bulk. The possible
existence of such micro branes can be investigated by considering the
properties of the ground state of a pseudo-Wheeler-DeWitt equation describing
brane quantum dynamics in minisuperspace. If they exist, a concentration of
these micro branes could act as a fluid of exotic matter able to support
macroscopic wormholes connecting otherwise distant regions of the bulk. Were
the brane constituting our universe to expand into a region of the bulk
containing such higher-dimensional macroscopic wormholes, they would likely
manifest themselves in our brane as wormholes of normal dimensionality, whose
spontaneous appearance and general dynamics would seem inexplicably peculiar.
This encounter could also result in the formation of baby universes of a
particular type.Comment: 21 pages, 1 figur
On local Fourier analysis of multigrid methods for PDEs with jumping and random coefficients
In this paper, we propose a novel non-standard Local Fourier Analysis (LFA)
variant for accurately predicting the multigrid convergence of problems with
random and jumping coefficients. This LFA method is based on a specific basis
of the Fourier space rather than the commonly used Fourier modes. To show the
utility of this analysis, we consider, as an example, a simple cell-centered
multigrid method for solving a steady-state single phase flow problem in a
random porous medium. We successfully demonstrate the prediction capability of
the proposed LFA using a number of challenging benchmark problems. The
information provided by this analysis helps us to estimate a-priori the time
needed for solving certain uncertainty quantification problems by means of a
multigrid multilevel Monte Carlo method
Parity-violating 3-jet observables for massive quarks to order alphas^2 in e+e- annihilation
In this talk we discuss the calculation of the QCD corrections to
parity-violating 3-jet observables in e^+e^- collisions, keeping the full quark
mass dependence.Comment: 5 pages, Talk given at International Euroconference in Quantum
Chromodynamics: 15 Years of the QCD - Montpellier Conference (QCD 00),
Montpellier, France, 6-12 Jul 200
- …