1,011 research outputs found
Measurements of laser-hole boring into overdense plasmas using x-ray laser refractometry(invited)
Copyright 1999 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments, 70(1), 543-548, 1986 and may be found at http://dx.doi.org/10.1063/1.114938
Effect of Background Evolution on the Curvaton Non-Gaussianity
We investigate how the background evolution affects the curvature
perturbations generated by the curvaton, assuming a curvaton potential that may
deviate slightly from the quadratic one, and parameterizing the background
fluid density as \rho\propto a^{-\alpha}, where a is the scale factor, and
\alpha depends on the background fluid. It turns out that the more there is
deviation from the quadratic case, the more pronounced is the dependence of the
curvature perturbation on \alpha. We also show that the background can have a
significant effect on the nonlinearity parameters f_NL and g_NL. As an example,
if at the onset of the curvaton oscillation there is a dimension 6 contribution
to the potential at 5 % level and the energy fraction of the curvaton to the
total one at the time of its decay is at 1 %, we find variations \Delta f_NL
\sim \mathcal{O}(10) and \Delta g_NL \sim \mathcal{O}(10^4) between matter and
radiation dominated backgrounds. Moreover, we demonstrate that there is a
relation between f_NL and g_NL that can be used to probe the form of the
curvaton potential and the equation of state of the background fluid.Comment: 14 pages, 8 figure
Brueckner Rearrangement Effects in He and He
Rearrangement effects in light hypernuclei are investigated in the framework
of the Brueckner theory. We can estimate without detailed numerical
calculations that the energy of the -core is reduced by more than 2.5
MeV when the adheres to He to form He. Similar
assessment of rearrangement contributions is essential to deduce the strength
of interaction from experimentally observed . The recently observed experimental value of 1 MeV
for the of \hll suggests that the matrix element of
in \hll is around -2 MeV.Comment: 7 pages, to appear in Phys. Rev.
Chaotic Repellers in Antiferromagnetic Ising Model
For the first time we present the consideration of the antiferromagnetic
Ising model in case of fully developed chaos and obtain the exact connection
between this model and chaotic repellers. We describe the chaotic properties of
this statistical mechanical system via the invariants characterizing a fractal
set and show that in chaotic region it displays phase transition at {\it
positive} "temperature" . We obtain the density of the
invariant measure on the chaotic repeller.Comment: LaTeX file, 10 pages, 4 PS figurs upon reques
The Subdominant Curvaton
We present a systematic study of the amplitude of the primordial perturbation
in curvaton models with self-interactions, treating both renormalizable and
non-renormalizable interactions. In particular, we consider the possibility
that the curvaton energy density is subdominant at the time of the curvaton
decay. We find that large regions in the parameter space give rise to the
observed amplitude of primordial perturbation even for non-renormalizable
curvaton potentials, for which the curvaton energy density dilutes fast. At the
time of its decay, the curvaton energy density may typically be subdominant by
a relative factor of 10^-3 and still produce the observed perturbation. Field
dynamics turns out to be highly non-trivial, and for non-renormalizable
potentials and certain regions of the parameter space we observe a
non-monotonous relation between the final curvature perturbation and the
initial curvaton value. In those cases, the time evolution of the primordial
perturbation also displays an oscillatory behaviour before the curvaton decay.Comment: Acknowledgments of financial support added, no further change
Density Fluctuations in Thermal Inflation and Non-Gaussianity
We consider primordial fluctuations in thermal inflation scenario. Since the
thermal inflation drives about 10 -folds after the standard inflation, the
time of horizon-exit during inflation corresponding to the present
observational scale shifts toward the end of inflation. It generally makes the
primordial power spectrum more deviated from a scale-invariant one and hence
renders some models inconsistent with observations. We present a mechanism of
generating the primordial curvature perturbation at the end of thermal
inflation utilizing a fluctuating coupling of a flaton field with the fields in
thermal bath. We show that, by adopting the mechanism, some inflation models
can be liberated even in the presence of the thermal inflation. We also discuss
non-Gaussianity in the mechanism and show that large non-Gaussianity can be
generated in this scenario.Comment: 15 pages, 1 figures, minor change
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