6,552 research outputs found
On the Realization of Assisted Inflation
We consider conditions necessary for a successful implementation of so-called
assisted inflation. We generalize the applicability of assisted inflation
beyond exponential potentials as originally proposed to include standard
chaotic (\lambda \phi^4 or m^2 \phi^2) models as well. We also demonstrate that
in a purely 4-dimensional theory, unless the assisted sector is in fact
decoupled, the additional fields of the assisted sector actually impede
inflation. As a specific example of an assisted sector, we consider a
5-dimensional KK model for which the extra dimension may be somewhat or much
larger than the inverse Planck scale. In this case, the assisted sector (coming
from a KK compactification) eliminates the need for a fine-tuned quartic
coupling to drive chaotic inflation. This is a general result of models with
one or more "large" extra dimensions.Comment: 25 pages, LaTeX fil
Non-Linear Langevin and Fractional Fokker-Planck Equations for Anomalous Diffusion by Levy Stable Processes
The~numerical solutions to a non-linear Fractional Fokker--Planck (FFP)
equation are studied estimating the generalized diffusion coefficients. The~aim
is to model anomalous diffusion using an FFP description with fractional
velocity derivatives and Langevin dynamics where L\'{e}vy fluctuations are
introduced to model the effect of non-local transport due to fractional
diffusion in velocity space. Distribution functions are found using numerical
means for varying degrees of fractionality of the stable L\'{e}vy distribution
as solutions to the FFP equation. The~statistical properties of the
distribution functions are assessed by a generalized normalized expectation
measure and entropy and modified transport coefficient. The~transport
coefficient significantly increases with decreasing fractality which is
corroborated by analysis of experimental data.Comment: 20 pages 7 figure
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