313 research outputs found
Kepler constraints on planets near hot Jupiters
We present the results of a search for planetary companions orbiting near hot Jupiter planet candidates (Jupiter-size candidates with orbital periods near 3 d) identified in the Kepler data through its sixth quarter of science operations. Special emphasis is given to companions between the 2∶1 interior and exterior mean-motion resonances. A photometric transit search excludes companions with sizes ranging from roughly two-thirds to five times the size of the Earth, depending upon the noise properties of the target
star. A search for dynamically induced deviations from a constant period (transit timing variations) also shows no significant signals. In contrast, comparison studies of warm Jupiters (with slightly larger orbits) and hot Neptune-size candidates do exhibit signatures of additional companions with these same tests. These differences
between hot Jupiters and other planetary systems denote a distinctly different formation or dynamical history
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Ratio of Pion Kaon Production in Proton Carbon Interactions
The ratio of pion-kaon production by 120 GeV/c protons incident on carbon target is presented. The data was recorded with the Main Injector Particle Production experiment at Fermi National Accelerator Laboratory. Production ratios of K{sup +}/{pi}{sup +}, K{sup -}/{pi}{sup -}, K{sup -}/K{sup +}, and {pi}{sup -}/{pi}{sup +} are measured in 24 bins in longitudinal momentum from 20 to 90 GeV/c and transverse momentum up to 2 GeV/c. The measurement is compared to existing data sets, particle production Monte Carlo results from FLUKA-06, parametrization of proton-beryllium data at 400/450 GeV/c, and ratios measured by the MINOS experiment on the NuMI target
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An Enquiry Concerning Charmless Semileptonic Decays of Bottom Mesons
The branching fractions for the decays B {yields} P{ell}{nu}{sub {ell}}, where P are the pseudoscalar charmless mesons {pi}{sup {+-}}, {pi}{sup 0}, {eta} and {eta}{prime} and {ell} is an electron or muon, are measured with B{sup 0} and B{sup {+-}} mesons found in the recoil of a second B meson decaying as B {yields} D{ell}{nu}{sub {ell}} or B {yields} D*{ell}{nu}{sub {ell}}. The measurements are based on a data set of 348 fb{sup -1} of e{sup +}e{sup -} collisions at {radical}s = 10.58 GeV recorded with the BABAR detector. Assuming isospin symmetry, measured pionic branching fractions are combined into {Beta}(B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu}{sub {ell}}) = (1.54 {+-} 0.17{sub (stat)} {+-} 0.09{sub (syst)}) x 10{sup -4}. First evidence of the B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}} decay is seen; its branching fraction is measured to be {Beta}(B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}}) = (0.64 {+-} 0.20{sub (stat)} {+-} 0.03{sub (syst)}) x 10{sup -4}. It is determined that {Beta}(B{sup +} {yields} {eta}{prime}{ell}{sup +}{nu}{sub {ell}}) < 0.47 x 10{sup -4} to 90% confidence. Partial branching fractions for the pionic decays in ranges of the momentum transfer and various published calculations of the B {yields} {pi} hadronic form factor are used to obtain values of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element V{sub ub} between 3.61 and 4.07 x 10{sup -3}
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Measurement of electron neutrino appearance with the MINOS experiment
MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. By measuring the neutrino interactions in a detector near the neutrino source and again 735 km away from the production site, it is possible to probe the parameters governing neutrino oscillation. The majority of the {nu}{sub {mu}} oscillate to {nu}{sub {tau}} but a small fraction may oscillate instead to {nu}{sub e}. This thesis presents a measurement of the {nu}{sub e} appearance rate in the MINOS far detector using the first two years of exposure. Methods for constraining the far detector backgrounds using the near detector measurements is discussed and a technique for estimating the uncertainty on the background and signal selection are developed. A 1.6{sigma} excess over the expected background rate is found providing a hint of {nu}{sub e} appearance
On the influence of the cosmological constant on gravitational lensing in small systems
The cosmological constant Lambda affects gravitational lensing phenomena. The
contribution of Lambda to the observable angular positions of multiple images
and to their amplification and time delay is here computed through a study in
the weak deflection limit of the equations of motion in the Schwarzschild-de
Sitter metric. Due to Lambda the unresolved images are slightly demagnified,
the radius of the Einstein ring decreases and the time delay increases. The
effect is however negligible for near lenses. In the case of null cosmological
constant, we provide some updated results on lensing by a Schwarzschild black
hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation,
references added, results unchanged, in press on PR
All Weather Calibration of Wide Field Optical and NIR Surveys
The science goals for ground-based large-area surveys, such as the Dark
Energy Survey, Pan-STARRS, and the Large Synoptic Survey Telescope, require
calibration of broadband photometry that is stable in time and uniform over the
sky to precisions of a per cent or better. This performance will need to be
achieved with data taken over the course of many years, and often in less than
ideal conditions. This paper describes a strategy to achieve precise internal
calibration of imaging survey data taken in less than photometric conditions,
and reports results of an observational study of the techniques needed to
implement this strategy. We find that images of celestial fields used in this
case study with stellar densities of order one per arcmin-squared and taken
through cloudless skies can be calibrated with relative precision of 0.5 per
cent (reproducibility). We report measurements of spatial structure functions
of cloud absorption observed over a range of atmospheric conditions, and find
it possible to achieve photometric measurements that are reproducible to 1 per
cent in images that were taken through cloud layers that transmit as little as
25 per cent of the incident optical flux (1.5 magnitudes of extinction). We
find, however, that photometric precision below 1 per cent is impeded by the
thinnest detectable cloud layers. We comment on implications of these results
for the observing strategies of future surveys.Comment: Accepted for publication in The Astronomical Journal (AJ
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Trapped Inflation
We analyze a distinctive mechanism for inflation in which particle production slows down a scalar field on a steep potential, and show how it descends from angular moduli in string compactifications. The analysis of density perturbations - taking into account the integrated effect of the produced particles and their quantum fluctuations - requires somewhat new techniques that we develop. We then determine the conditions for this effect to produce sixty e-foldings of inflation with the correct amplitude of density perturbations at the Gaussian level, and show that these requirements can be straightforwardly satisfied. Finally, we estimate the amplitude of the non-Gaussianity in the power spectrum and find a significant equilateral contribution
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