375 research outputs found
Inflation from Susy quantum cosmology
We propose a realization of inverted hybrid inflation scenario in the context
of n=2 supersymmetric quantum cosmology. The spectrum of density fluctuations
is calculated in the de Sitter regimen as a function of the gravitino and the
Planck mass, and explicit forms for the wave function of the universe are found
in the WKB regimen for a FRW closed and flat universes.Comment: 9 pages, one figure, to appear in Phys. Rev.
More varieties of hybrid inflation
It is pointed out that hybrid inflation can be implemented with the inflaton
field rolling away from the origin instead of towards it. This `inverted'
hybrid inflation has a spectral index , in contrast with ordinary
hybrid inflation which has , so a measured value of
substantially different from 1 would distinguish the two. Other generalisations
of hybrid inflation are also considered.Comment: 9 page
Inflationary models with a flat potential enforced by non-abelian discrete gauge symmetries
Non-abelian discrete gauge symmetries can provide the inflaton with a flat
potential even when one takes into account gravitational strength effects. The
discreteness of the symmetries also provide special field values where
inflation can end via a hybrid type mechanism. An interesting feature of this
method is that it can naturally lead to extremely flat potentials and so, in
principle, to inflation at unusually low energy scales. Two examples of
effective field theories with this mechanism are given, one with a hybrid exit
and one with a mutated hybrid exit. They include an explicit example in which
the single field consistency condition is violated.Comment: 24 pages, uses revtex.sty, submitted to PRD (Nov. 1999) Final version
to appear in PRD. Background information on supergravity expande
Effects of Nitrogen and Planting Seed Size on Cotton Growth, Development, and Yield
A standardized experiment was conducted during 2009 and 2010 at 20 location-years across U.S. cotton (Gossypium hirsutum L.)-producing states to compare the N use requirement of contemporary cotton cultivars based on their planting seed size. Treatments consisted of three cotton varieties with planting seed of different numbers of seed per kg and N rates of 0, 45, 90, and 134 kg haâ»Âč. Soil at each trial location was sampled and tested for nitrate presence. High levels of soil nitrate (>91 N-NOââ»kg haâ»Âč) were found in Arizona and western Texas, and soil nitrate in the range of 45 to 73 kg N-NOââ» haâ»Âč was found at locations in the central United States. Cotton lint yield responded to applied N at 11 of 20 locations. Considering only sites that responded to applied N, highest lint yields were achieved with 112 to 224 kg haâ»Âčof applied plus pre-plant residual soil NOââtranslating to an optimal N requirement of 23 kg haâ»Âč per 218 kg bale of lint produced. Among the varieties tested those with medium-sized seed produced higher yields in response to N than did larger and smaller seeded varieties. Varieties with larger seed had longer and stronger fibers, higher fiber length uniformity than small seeded varieties and decreased micronaire. Seed protein and oil increased and decreased slightly in response to increasing amounts of soil nitrate plus applied N, respectively
Flattening the Inflaton's Potential with Quantum Corrections
I show that a classical scalar potential with can be
sufficiently flattened by quantum corrections to give rise to slow-roll
inflation. This provides perhaps the simplest way to generate an inflationary
potential without fine tuning. The most natural implementation of this idea
produces an unviably small spectral index, but, for example, can
be obtained in other implementations.Comment: 8 pages, LaTe
A Hamilton-Jacobi approach to non-slow-roll inflation
I describe a general approach to characterizing cosmological inflation
outside the standard slow-roll approximation, based on the Hamilton-Jacobi
formulation of scalar field dynamics. The basic idea is to view the equation of
state of the scalar field matter as the fundamental dynamical variable, as
opposed to the field value or the expansion rate. I discuss how to formulate
the equations of motion for scalar and tensor fluctuations in situations where
the assumption of slow roll is not valid. I apply the general results to the
simple case of inflation from an ``inverted'' polynomial potential, and to the
more complicated case of hybrid inflation.Comment: 21 pages, RevTeX (minor revisions to match published version
Heavy-Meson Observables at One-Loop in Partially Quenched Chiral Perturbation Theory
I present one-loop level calculations of the Isgur-Wise functions for B ->
D^{(*)} + e + nu, of the matrix elements of isovector twist-2 operators in B
and D mesons, and the matrix elements for the radiative decays D^* -> D + gamma
in partially quenched heavy quark chiral perturbation theory. Such expressions
are required in order to extrapolate from the light quark masses used in
lattice simulations of the foreseeable future to those of nature.Comment: 13 pages, 3 fig
Consistency equations in Randall-Sundrum cosmology: a test for braneworld inflation
In the context of an inflationary Randall-Sundrum Type II braneworld (RS2) we
calculate spectral indices and amplitudes of cosmological scalar and tensor
perturbations, up to second order in slow-roll parameters. Under very simple
assumptions, extrapolating next-order formulae from first-order calculations in
the case of a de Sitter brane, we see that the degeneracy between standard and
braneworld lowest-order consistency equations is broken, thus giving different
signatures of early-universe inflationary expansion. Using the latest results
from WMAP for estimates of cosmological observables, it is shown that future
data and missions can in principle discriminate between standard and braneworld
scenarios.Comment: 13 pages; v3: supersedes the published version, corrected misprint
Thermal Inflation and the Moduli Problem
In supersymmetric theories a field can develop a vacuum expectation value , even though its mass is of order to
. The finite temperature in the early Universe can hold such a
field at zero, corresponding to a false vacuum with energy density . When the temperature falls below , the thermal energy
density becomes negligible and an era of thermal inflation begins. It ends when
the field rolls away from zero at a temperature of order , corresponding to
of order 10 -folds of inflation which does not affect the density
perturbation generated during ordinary inflation. Thermal inflation can solve
the Polonyi/moduli problem if is within one or two orders of magnitude of
.Comment: Revised version to appear in Phys Rev D. Improved discussion of the
possible effect of parametric resonance. Latex, 31 page
Supersymmetric D-term Inflation, Reheating and Affleck-Dine Baryogenesis
The phenomenology of supersymmetric models of inflation, where the
inflationary vacuum energy is dominated by D-terms of a U(1), is investigated.
Particular attention is paid to the questions of how to arrange for sufficient
e-folds of inflation to occur, what kind of thermal history is expected after
the end of inflation, and how to implement successful baryogenesis. Such models
are argued to require a more restrictive symmetry structure than previously
thought. In particular, it is non-trivial that the decays of the fields driving
D-inflation can reheat the universe in such a way as to avoid the strong
gravitino production constraints. We also show how the initial conditions for
Affleck-Dine baryogenesis can arise in these models and that the simplest flat
directions along which baryon number is generated can often be ruled out by the
constraints coming from decoherence of the condensate in a hot environment. At
the end, we find that successful reheating and baryogenesis can take place in a
large subset of D-inflationary models.Comment: 23 pages LaTe
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