384 research outputs found
Coulomb Force as an Entropic Force
Motivated by Verlinde's theory of entropic gravity, we give a tentative
explanation to Coulomb's law with an entropic force. When trying to do this, we
find the equipartition rule should be extended to charges and the concept of
temperature should be reinterpreted. If one accepts the holographic principle
as well as our generalizations and reinterpretations, then Coulomb's law, the
Poisson equation and the Maxwell equations can be derived smoothly. Our attempt
can be regarded as a new way to unify the electromagnetic force with gravity,
from the entropic origin. Possibly some of our postulates are related to the
D-brane picture of black hole thermodynamics.Comment: discussion and bibliography update
Cosmic Steps in Modeling Dark Energy
The past and recent data analyses gave some hints of steps in dark energy.
Considering the dark energy as a dynamical scalar field, we investigate several
models with various steps: a step in the scalar potential, a step in the
kinetic term, a step in the energy density and a step in the equation-of-state
parameter w. These toy models provide a workable mechanism to generate steps
and features of dark energy. Remarkably, a single real scalar can cross w=-1
dynamically with a step in the kinetic term.Comment: 6 pages, 5 figures, structure improved, reference added, results
unchange
General Single Field Inflation with Large Positive Non-Gaussianity
Recent analysis of the WMAP three year data suggests
in the WMAP convention. It is necessary to make sure
whether general single field inflation can produce a large positive
before turning to other scenarios. We give some examples to generate a large
positive in general single field inflation. Our models are
different from ghost inflation. Due to the appearance of non-conventional
kinetic terms, can be realized in single field inflation.Comment: 27 pages, 3 figure; final version published in JCA
Inflation with High Derivative Couplings
We study a class of generalized inflation models in which the inflaton is
coupled to the Ricci scalar by a general term. The scalar power
spectrum, the spectral index, the running of the spectral index, the tensor
mode spectrum and a new consistency relation of the model are calculated. We
discuss in detail the issues of how to diagonize the coupled perturbation
equations, how to deal with an entropy-like source, and how to determine the
initial condition by quantization. By studying some explicit models, we find
that rich phenomena such as a blue scalar power spectrum, a large running of
the spectral index, and a blue tensor mode spectrum can be obtained.Comment: 26 pages, LaTeX; v2: refs. added; refs. correcte
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