7,766 research outputs found

### Bounds on isocurvature perturbations from CMB and LSS data

We obtain very stringent bounds on the possible cold dark matter, baryon and
neutrino isocurvature contributions to the primordial fluctuations in the
Universe, using recent cosmic microwave background and large scale structure
data. In particular, we include the measured temperature and polarization power
spectra from WMAP and ACBAR, as well as the matter power spectrum from the 2dF
galaxy redshift survey. Neglecting the possible effects of spatial curvature,
tensor perturbations and reionization, we perform a Bayesian likelihood
analysis with nine free parameters, and find that the amplitude of the
isocurvature component cannot be larger than about 31% for the cold dark matter
mode, 91% for the baryon mode, 76% for the neutrino density mode, and 60% for
the neutrino velocity mode, at 2-sigma, for uncorrelated models. On the other
hand, for correlated adiabatic and isocurvature components, the fraction could
be slightly larger. However, the cross-correlation coefficient is strongly
constrained, and maximally correlated/anticorrelated models are disfavored.
This puts strong bounds on the curvaton model, independently of the bounds on
non-Gaussianity.Comment: 4 pages, 1 figure, some minor corrections; version accepted in PR

### Gauge invariant MSSM inflaton

We argue that all the necessary ingredients for successful inflation are
present in the flat directions of the Minimally Supersymmetric Standard Model.
We show that out of many gauge invariant combinations of squarks, sleptons and
Higgses, there are two directions, ${\bf LLe}$, and ${\bf udd}$, which are
promising candidates for the inflaton. The model predicts more than $10^3$
e-foldings with an inflationary scale of $H_{\rm inf}\sim {\cal O}(1-10)$ GeV,
provides a tilted spectrum with an amplitude of $\delta_H\sim 10^{-5}$ and a
negligible tensor perturbation. The temperature of the thermalized plasma could
be as low as $T_{rh}\sim {\cal O}(1-10)$~TeV. Parts of the inflaton potential
can be determined independently of cosmology by future particle physics
experiments.Comment: 4 revtex pages, some references added, stabilization of moduli and
supergravity effects are discusse

### Uncertainties of predictions in models of eternal inflation

In a previous paper \cite{MakingPredictions}, a method of comparing the
volumes of thermalized regions in eternally inflating universe was introduced.
In this paper, we investigate the dependence of the results obtained through
that method on the choice of the time variable and factor ordering in the
diffusion equation that describes the evolution of eternally inflating
universes. It is shown, both analytically and numerically, that the variation
of the results due to factor ordering ambiguity inherent in the model is of the
same order as their variation due to the choice of the time variable.
Therefore, the results are, within their accuracy, free of the spurious
dependence on the time parametrization.Comment: 30 pages, RevTeX, figure included, added some references and Comments
on recent proposal (gr-qc/9511058) of alternative regularization schemes, to
appear in Phys. Rev.

### Unambiguous probabilities in an eternally inflating universe

``Constants of Nature'' and cosmological parameters may in fact be variables
related to some slowly-varying fields. In models of eternal inflation, such
fields will take different values in different parts of the universe. Here I
show how one can assign probabilities to values of the ``constants'' measured
by a typical observer. This method does not suffer from ambiguities previously
discussed in the literature.Comment: 7 pages, Final version (minor changes), to appear in Phys. Rev. Let

### Propofol induce higher amnesic effect than sevoflurane and isoflurane anaesthesia in the rat

Universidad de MÃ¡laga. Campus de Excelencia Internacional AndalucÃa Tec

### Lambda-inflation and CMB anisotropy

We explore a broad class of three-parameter inflationary models, called the
$\Lambda$-inflation, and its observational predictions: high abundance of
cosmic gravitational waves consistent with the Harrison-Zel'dovich spectrum of
primordial cosmological perturbations, the non-power-law wing-like spectrum of
matter density perturbations, high efficiency of these models to meet current
observational tests, and others. We show that a parity contribution of the
gravitational waves and adiabatic density perturbations into the large-scale
temperature anisotropy, T/S $\sim 1$, is a common feature of
$\Lambda$-inflation; the maximum values of T/S (basically not larger than 10)
are reached in models where (i) the local spectrum shape of density
perturbations is flat or slightly red ($n_S{}_\sim^< 1$), and (ii) the residual
potential energy of the inflaton is near the GUT scale ($V_0^{{1/4}} \sim
10^{16} GeV$). The conditions to find large T/S in the paradigm of cosmic
inflation and the relationship of T/S to the ratio of the power spectra, $r$,
and to the inflationary $\gamma$ and Hubble parameters, are discussed. We argue
that a simple estimate, T/S$\simeq 3r\simeq 12\gamma \simeq (\frac{H}{6\times
10^{13}{\rm GeV}})^2$, is true for most known inflationary solutions and allows
to relate straightforwardly the important parameters of observational and
physical cosmology.Comment: 29 pages, 3 figures include

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