2,653 research outputs found
Inflation with Holographic Dark Energy
We investigate the corrections of the holographic dark energy to inflation
paradigm. We study the evolution of the holographic dark energy in the
inflationary universe in detail, and carry out a model-independent analysis on
the holographic dark energy correction to the primordial scalar power spectrum.
It turns out that the corrections generically make the spectrum redder. To be
consistent with the experimental data, there must be a upper bound on the
reheating temperature. We also discuss the corrections due to different choices
of the infrared cutoff.Comment: 15 pages, 3 figures, v2: references added, a fast-roll discussion
added. v3: typos corrected. v4: final version to appear in NP
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
The Fate of Massive Closed Strings
We calculate the semi-inclusive decay rate of an average string state with
toroidal compactification in the the superstring theory. We also apply this
calculation to a brane-inflation model in a warped geometry and find that the
decay rate is greatly suppressed if the final strings are both massive and
enhanced for massless radiation.Comment: 4 pages, to appear in the proceeding of PASCOS 2005, Gyeongju, Korea,
May 30-June 4, 200
Two-scale exponential integrators with uniform accuracy for three-dimensional charged-particle dynamics under strong magnetic field
The numerical simulation of three-dimensional charged-particle dynamics (CPD)
under strong magnetic field is challenging. In this paper, we introduce a new
methodology to design two-scale exponential integrators for three-dimensional
CPD whose magnetic field's strength is inversely proportional to a
dimensionless parameter . By dealing with the transformed
form of three-dimensional CPD, we linearize the magnetic field and put the rest
part in a nonlinear function which can be shown to be small. Based on which and
the proposed two-scale exponential integrators, a class of novel integrators is
formulated. The corresponding uniform accuracy over
time interval is
for the -th order integrator with
the time stepsize , and . A rigorous proof of this
error bound is presented and a numerical test is performed to illustrate the
error behaviour of the proposed integrators
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