Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star System
ArXiv 1210.3612 (2012)
Abstract:
We report the discovery and confirmation of a transiting circumbinary planet (PH1b) around KIC 4862625, an eclipsing binary in the Kepler field. The planet was discovered by volunteers searching the first six Quarters of publicly available Kepler data as part of the Planet Hunters citizen science project. Transits of the planet across the larger and brighter of the eclipsing stars are detectable by visual inspection every ~137 days, with seven transits identified in Quarters 1-11. The physical and orbital parameters of both the host stars and planet were obtained via a photometric-dynamical model, simultaneously fitting both the measured radial velocities and the Kepler light curve of KIC 4862625. The 6.18 +/- 0.17 Earth radii planet orbits outside the 20-day orbit of an eclipsing binary consisting of an F dwarf (1.734 +/- 0.044 Solar radii, 1.528 +/- 0.087 Solar masses) and M dwarf (0.378+/- 0.023 Solar radii, 0.408 +/- 0.024 Solar masses). For the planet, we find an upper mass limit of 169 Earth masses (0.531 Jupiter masses) at the 99.7% confidence level. With a radius and mass less than that of Jupiter, PH1b is well within the planetary regime. Outside the planet's orbit, at ~1000 AU,a previously unknown visual binary has been identified that is likely bound to the planetary system, making this the first known case of a quadruple star system with a transiting planet.Observation of the Dalitz decay Ds*+→Ds+e+ e-
Physical Review D - Particles, Fields, Gravitation and Cosmology 86:7 (2012)
Abstract:
Using 586pb -1 of e +e - collision data acquired at √s=4.170GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of Ds*+→Ds+e +e - with a significance of 5.3σ. The ratio of branching fractions B(Ds*+→Ds+e +e -)/ B(Ds*+→Ds+γ) is measured to be [0.72-0.13+0.15(stat)±0. 10(syst)]%, which is consistent with theoretical expectations. © 2012 American Physical Society.Underlying event characteristics and their dependence on jet size of charged-particle jet events in pp collisions at √(s)=7TeV with the ATLAS detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 86:7 (2012)
Abstract:
Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at √s=7TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800μb-1 of data taken during 2010. Jets are reconstructed using the anti-kt algorithm with radius parameter R varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of pTjet in regions transverse to and opposite the leading jet for 4GeVSearch for a W' or Techni-ρ decaying into WZ in pp collisions at √s=7TeV
Physical Review Letters 109:14 (2012)