162 research outputs found
Reconstructing the Inflaton Potential
A review is presented of recent work by the authors concerning the use of
large scale structure and microwave background anisotropy data to determine the
potential of the inflaton field. The importance of a detection of the
stochastic gravitational wave background is emphasised, and some preliminary
new results of tests of the method on simulated data sets with uncertainties
are described. (Proceedings of ``Unified Symmetry in the Small and in the
Large'', Coral Gables, 1994)Comment: 13 pages, uuencoded postscript file with figures included (LaTeX file
available from ARL), FERMILAB-Conf 94/189
Fanny Copeland and the geographical imagination
Raised in Scotland, married and divorced in the English south, an adopted Slovene, Fanny Copeland (1872 – 1970) occupied the intersection of a number of complex spatial and temporal conjunctures. A Slavophile, she played a part in the formation of what subsequently became the Kingdom of Yugoslavia that emerged from the First World War. Living in Ljubljana, she facilitated the first ‘foreign visit’ (in 1932) of the newly formed Le Play Society (a precursor of the Institute of British Geographers) and guided its studies of Solčava (a then ‘remote’ Alpine valley system) which, led by Dudley Stamp and commended by Halford Mackinder, were subsequently hailed as a model for regional studies elsewhere. Arrested by the Gestapo and interned in Italy during the Second World War, she eventually returned to a socialist Yugoslavia, a celebrated figure. An accomplished musician, linguist, and mountaineer, she became an authority on (and populist for) the Julian Alps and was instrumental in the establishment of the Triglav National Park. Copeland’s role as participant observer (and protagonist) enriches our understanding of the particularities of her time and place and illuminates some inter-war relationships within G/geography, inside and outside the academy, suggesting their relative autonomy in the production of geographical knowledge
On the reliability of inflaton potential reconstruction
If primordial scalar and tensor perturbation spectra can be inferred from
observations of the cosmic background radiation and large-scale structure, then
one might hope to reconstruct a unique single-field inflaton potential capable
of generating the observed spectra. In this paper we examine conditions under
which such a potential can be reliably reconstructed. For it to be possible at
all, the spectra must be well fit by a Taylor series expansion. A complete
reconstruction requires a statistically-significant tensor mode to be measured
in the microwave background. We find that the observational uncertainties
dominate the theoretical error from use of the slow-roll approximation, and
conclude that the reconstruction procedure will never insidiously lead to an
irrelevant potential.Comment: 16 page LaTeX file with eight postscript figures embedded with epsf;
no special macros neede
Relating Spectral Indices to Tensor and Scalar Amplitudes in Inflation
Within an expansion in slow-roll inflation parameters, we derive the complete
second-order expressions relating the ratio of tensor to scalar density
perturbations and the spectral index of the scalar spectrum. We find that
``corrections'' to previously derived formulae can dominate if the tensor to
scalar ratio is small. For instance, if or if
m_{Pl}^2/(4\pi) ~|V'''/V'|\ga 1, where is the inflaton potential
and is the Planck mass, then the previously used simple relations
between the indices and the tensor to scalar ratio fails. This failure occurs
in particular for natural inflation, Coleman--Weinberg inflation, and
``chaotic'' inflation.Comment: 18 pages, LaTeX, no figures, FNAL--PUB--94/046-A; CfPA 94-th-14
(small revisions only, esp. examples for hybrid inflation
Stress and Burnout Among Surgical Oncologists: A Call for Personal Wellness and a Supportive Workplace Environment
Observing the Inflaton Potential
We show how observations of the density perturbation (scalar) spectrum and
the gravitational wave (tensor) spectrum allow a reconstruction of the
potential responsible for cosmological inflation. A complete functional
reconstruction or a perturbative approximation about a single scale are
possible; the suitability of each approach depends on the data available.
Consistency equations between the scalar and tensor spectra are derived, which
provide a powerful signal of inflation.Comment: 9 pages, LaTeX, FERMILAB--PUB--93/071--A; SUSSEX-AST 93/4-
Probing Planckian physics: resonant production of particles during inflation and features in the primordial power spectrum
The phenomenon of resonant production of particles {\it after} inflation has
received much attention in the past few years. In a new application of resonant
production of particles, we consider the effect of a resonance {\em during}
inflation. We show that if the inflaton is coupled to a massive particle,
resonant production of the particle during inflation modifies the evolution of
the inflaton, and may leave an imprint in the form of sharp features in the
primordial power spectrum. Precision measurements of microwave background
anisotropies and large-scale structure surveys could be sensitive to the
features, and probe the spectrum of particles as massive as the Planck scale.Comment: 19 pages, 11 eps figure
Reconstructing the Inflaton Potential---in Principle and in Practice
Generalizing the original work by Hodges and Blumenthal, we outline a
formalism which allows one, in principle, to reconstruct the potential of the
inflaton field from knowledge of the tensor gravitational wave spectrum or the
scalar density fluctuation spectrum, with special emphasis on the importance of
the tensor spectrum. We provide some illustrative examples of such
reconstruction. We then discuss in some detail the question of whether one can
use real observations to carry out this procedure. We conclude that in
practice, a full reconstruction of the functional form of the potential will
not be possible within the foreseeable future. However, with a knowledge of the
dark matter components, it should soon be possible to combine
intermediate-scale data with measurements of large-scale cosmic microwave
background anisotropies to yield useful information regarding the potential.Comment: 39 pages plus 2 figures (upon request:[email protected]), LaTeX,
FNAL--PUB--93/029-A; SUSSEX-AST 93/3-
Cosmic microwave background measurements can discriminate among inflation models
Quantum fluctuations during inflation may be responsible for temperature
anisotropies in the cosmic microwave background (CMB). Observations of CMB
anisotropies can be used to falsify many currently popular models. In this
paper we discuss the prospectus for observations of CMB anisotropies at the
accuracy of planned satellite missions to reject currently popular inflation
models and to provide some direction for model building.Comment: 25-page LaTeX file. Six postscript figure
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