4,149 research outputs found
Numerical residual perturbation solutions applied to the problem of a close satellite of the smaller body in the restricted three-body problem
Numerical residual perturbation solution for prediction of satellite position in restricted three-body proble
Non-Equilibrium Evolution of Scalar Fields in FRW Cosmologies I
We derive the effective equations for the out of equilibrium time evolution
of the order parameter and the fluctuations of a scalar field theory in
spatially flat FRW cosmologies.The calculation is performed both to one-loop
and in a non-perturbative, self-consistent Hartree approximation.The method
consists of evolving an initial functional thermal density matrix in time and
is suitable for studying phase transitions out of equilibrium. The
renormalization aspects are studied in detail and we find that the counterterms
depend on the initial state. We investigate the high temperature expansion and
show that it breaks down at long times. We also obtain the time evolution of
the initial Boltzmann distribution functions, and argue that to one-loop order
or in the Hartree approximation, the time evolved state is a ``squeezed''
state. We illustrate the departure from thermal equilibrium by numerically
studying the case of a free massive scalar field in de Sitter and radiation
dominated cosmologies. It is found that a suitably defined non-equilibrium
entropy per mode increases linearly with comoving time in a de Sitter
cosmology, whereas it is {\it not} a monotonically increasing function in the
radiation dominated case.Comment: 29 pages, revtex 3.0, 11 figures available upon request, PITT-93-6;
LPTHE-93-52; CMU-HEP-93-2
Assessment of the visibility impairment caused by the emissions from the proposed power plant at Boron, California
The current atmospheric conditions and visibility were modeled, and the effect of the power plant effluent was then added to determine its influence upon the prevailing visibility; the actual reduction in visibility being a function of meteorological conditions and observer-plume-target geometry. In the cases investigated, the perceptibility of a target was reduced by a minimum of 10 percent and a maximum of 100 percent. This significant visual impact would occur 40 days per year in the Edwards area with meteorological conditions such as to cause some visual impact 80 days per year
Renormalization of initial conditions and the trans-Planckian problem of inflation
Understanding how a field theory propagates the information contained in a
given initial state is essential for quantifying the sensitivity of the cosmic
microwave background to physics above the Hubble scale during inflation. Here
we examine the renormalization of a scalar theory with nontrivial initial
conditions in the simpler setting of flat space. The renormalization of the
bulk theory proceeds exactly as for the standard vacuum state. However, the
short distance features of the initial conditions can introduce new divergences
which are confined to the surface on which the initial conditions are imposed.
We show how the addition of boundary counterterms removes these divergences and
induces a renormalization group flow in the space of initial conditions.Comment: 22 pages, 4 eps figures, uses RevTe
Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC
We report the detection of transit timing variations (TTVs) well in excess of
one hour in the Kepler multi-planet candidate system KOI 806. This system
exhibits transits consistent with three separate planets -- a Super-Earth, a
Jupiter, and a Saturn -- lying very nearly in a 1:2:5 resonance, respectively.
We used the Kepler public data archive and observations with the Gran
Telescopio de Canarias to compile the necessary photometry. For the largest
candidate planet (KOI 806.02) in this system, we detected a large transit
timing variation of -103.56.9 minutes against previously published
ephemeris. We did not obtain a strong detection of a transit color signature
consistent with a planet-sized object; however, we did not detect a color
difference in transit depth, either. The large TTV is consistent with
theoretical predictions that exoplanets in resonance can produce large transit
timing variations, particularly if the orbits are eccentric. The presence of
large TTVs among the bodies in this systems indicates that KOI806 is very
likely to be a planetary system. This is supported by the lack of a strong
color dependence in the transit depth, which would suggest a blended eclipsing
binary.Comment: 9 pages, 4 figures, accepted into A&A Letter
Irreducible decomposition for tensor prodect representations of Jordanian quantum algebras
Tensor products of irreducible representations of the Jordanian quantum
algebras U_h(sl(2)) and U_h(su(1,1)) are considered. For both the highest
weight finite dimensional representations of U_h(sl(2)) and lowest weight
infinite dimensional ones of U_h(su(1,1)), it is shown that tensor product
representations are reducible and that the decomposition rules to irreducible
representations are exactly the same as those of corresponding Lie algebras.Comment: LaTeX, 14pages, no figur
Constraints in the Context of Induced-gravity Inflation
Constraints on the required flatness of the scalar potential for a
cousin-model to extended inflation are studied. It is shown that, unlike
earlier results, Induced-gravity Inflation can lead to successful inflation
with a very simple lagrangian and , rather than
as previously reported. A second order phase transition further
enables this model to escape the \lq big bubble' problem of extended inflation,
while retaining the latter's motivations based on the low-energy effective
lagrangians of supergravity, superstring, and Kaluza-Klein theories.Comment: 19 pp; 3 figures (not included -- available from author). Plain
LaTeX. In press in Physical Review
The Orbit and Occultations of KH 15D
The unusual flux variations of the pre-main-sequence binary star KH 15D have
been attributed to occultations by a circumbinary disk. We test whether or not
this theory is compatible with newly available data, including recent radial
velocity measurements, CCD photometry over the past decade, and photographic
photometry over the past 50 years. We find the model to be successful, after
two refinements: a more realistic motion of the occulting feature, and a halo
around each star that probably represents scattering by the disk. The occulting
feature is exceptionally sharp-edged, raising the possibility that the dust in
the disk has settled into a thin layer, and providing a tool for fine-scale
mapping of the immediate environment of a T Tauri star. However, the window of
opportunity is closing, as the currently visible star may be hidden at all
orbital phases by as early as 2008.Comment: To appear in ApJ [16 pages, 13 figures
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