239 research outputs found
Proton Scattering from 206-Pb: Neutron Densities in the Nuclear Interior
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Inflationary Attractor from Tachyonic Matter
We study the complete evolution of a flat and homogeneous universe dominated
by tachyonic matter. We demonstrate the attractor behaviour of the tachyonic
inflation using the Hamilton-Jacobi formalism. We else obtain analytical
approximations to the trajectories of the tachyon field in different regions.
The numerical calculation shows that an initial non-vanishing momentum does not
prevent the onset of inflation. The slow-rolling solution is an attractor.Comment: 4 pages, 2 figures, RevTe
Double Inflation in Supergravity and the Large Scale Structure
The cosmological implication of a double inflation model with hybrid + new
inflations in supergravity is studied. The hybrid inflation drives an inflaton
for new inflation close to the origin through supergravity effects and new
inflation naturally occurs. If the total e-fold number of new inflation is
smaller than , both inflations produce cosmologically relevant density
fluctuations. Both cluster abundances and galaxy distributions provide strong
constraints on the parameters in the double inflation model assuming
standard cold dark matter scenario. The future satellite
experiments to measure the angular power spectrum of the cosmic microwave
background will make a precise determination of the model parameters possible.Comment: 19 pages (RevTeX file
Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c
We have searched for the K+ to pi+ gamma gamma decay in the kinematic region
with pi+ momentum close to the end point. No events were observed, and the 90%
confidence-level upper limit on the partial branching ratio was obtained, B(K+
to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral
perturbation theory including next-to-leading order ``unitarity'' corrections.
The same data were used to determine an upper limit on the K+ to pi+ gamma
branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for
publication in Physics Letters
Large Scale Structure and Supersymmetric Inflation without Fine Tuning
We explore constraints on the spectral index of density fluctuations and
the neutrino energy density fraction , employing data from a
variety of large scale observations. The best fits occur for and
, over a range of Hubble constants km
s Mpc. We present a new class of inflationary models based on
realistic supersymmetric grand unified theories which do not have the usual
`fine tuning' problems. The amplitude of primordial density fluctuations, in
particular, is found to be proportional to , where
denote the GUT (Planck) scale, which is reminiscent of cosmic strings! The
spectral index , in excellent agreement with the observations
provided the dark matter is a mixture of `cold' and `hot' components.Comment: LaTEX, 14 pp. + 1 postscript figure appende
Physics of Solar Prominences: I - Spectral Diagnostics and Non-LTE Modelling
This review paper outlines background information and covers recent advances
made via the analysis of spectra and images of prominence plasma and the
increased sophistication of non-LTE (ie when there is a departure from Local
Thermodynamic Equilibrium) radiative transfer models. We first describe the
spectral inversion techniques that have been used to infer the plasma
parameters important for the general properties of the prominence plasma in
both its cool core and the hotter prominence-corona transition region. We also
review studies devoted to the observation of bulk motions of the prominence
plasma and to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically thick at
certain wavelengths. Therefore, complex non-LTE models become necessary. We
thus present the basics of non-LTE radiative transfer theory and the associated
multi-level radiative transfer problems. The main results of one- and
two-dimensional models of the prominences and their fine-structures are
presented. We then discuss the energy balance in various prominence models.
Finally, we outline the outstanding observational and theoretical questions,
and the directions for future progress in our understanding of solar
prominences.Comment: 96 pages, 37 figures, Space Science Reviews. Some figures may have a
better resolution in the published version. New version reflects minor
changes brought after proof editin
The Large Scale Structure in the Universe: From Power-Laws to Acoustic Peaks
The most popular tools for analysing the large scale distribution of galaxies
are second-order spatial statistics such as the two-point correlation function
or its Fourier transform, the power spectrum. In this review, we explain how
our knowledge of cosmic structures, encapsulated by these statistical
descriptors, has evolved since their first use when applied on the early galaxy
catalogues to the present generation of wide and deep redshift surveys,
incorporating the most challenging discovery in the study of the galaxy
distribution: the detection of Baryon Acoustic Oscillations.Comment: 20 pages, 12 figures, to appear in "Data Analysis in Cosmology",
Lecture Notes in Physics, 2008, eds. V. J. Martinez, E. Saar, E.
Martinez-Gonzalez, and M.J. Pons-Borderia, Springer-Verla
Using behavior-analytic implicit tests to assess sexual interests among normal and sex-offender populations
The development of implicit tests for measuring biases and behavioral predispositions is a recent development within psychology. While such tests are usually researched within a social-cognitive paradigm, behavioral researchers have also begun to view these tests as potential tests of conditioning histories, including in the sexual domain.
The objective of this paper is to illustrate the utility of a behavioral approach to implicit testing and means by which implicit tests can be built to the standards of behavioral psychologists.
Research findings illustrating the short history of implicit testing within the experimental analysis of behavior are reviewed. Relevant parallel and overlapping research findings from the field of social cognition and on the Implicit Association Test are also outlined.
New preliminary data obtained with both normal and sex offender populations are described in order to illustrate how behavior-analytically conceived implicit tests may have potential as investigative tools for assessing histories of sexual arousal conditioning and derived stimulus associations.
It is concluded that popular implicit tests are likely sensitive to conditioned and derived stimulus associations in the history of the test-taker rather than 'unconscious cognitions', per se
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