OPMD

Abstract:

The decays of ψ(2S) into γpp̄, π0pp̄, and ηpp̄ have been studied with the CLEO-c detector using a sample of 24.5×106 ψ(2S) events obtained from e⊃+e⊃- annihilations at √s=3686MeV. The data show evidence for the excitation of several N⊃* resonances in pπ0 and pη channels in π0pp̄ and ηpp̄ decays, and f2 states in γpp̄ decay. Branching fractions for decays of ψ(2S) to γpp̄, π0pp̄, and ηpp̄ have been determined. No evidence for pp̄ threshold enhancements was found in the reactions ψ(2S)→Xpp̄, where X=γ, π0, η. We do, however, find confirming evidence for a pp̄ threshold enhancement in J/ψ→γpp̄ as previously reported by BES. © 2010 The American Physical Society.

Abstract:

We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy √s=1.96TeV. This search was conducted within the framework of the R parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of 1fb⊃-1 collected by the Collider Detector at Fermilab experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to 180GeV/c2 are excluded for sneutrino masses around 45GeV/c2, and sneutrino masses up to 116GeV/c2 are excluded for stop quark masses around 150GeV/c2. © 2010 The American Physical Society.

Abstract:

The Large Synoptic Survey Telescope (LSST) is a proposed ground based telescope that will perform a comprehensive astronomical survey by imaging the entire visible sky in a continuous series of short exposures. Four special purpose rafts, mounted at the corners of the LSST science camera, contain wavefront sensors and guide sensors. Wavefront measurements are accomplished using curvature sensing, in which the spatial intensity distribution of stars is measured at equal distances on either side of focus by CCD detectors. The four Corner Rafts also each hold two guide sensors. The guide sensors monitor the locations of bright stars to provide feedback that controls and maintains the tracking of the telescope during an exposure. The baseline sensor for the guider is a Hybrid Visible Silicon hybrid-CMOS detector. We present here a conceptual mechanical and electrical design for the LSST Corner Rafts that meets the requirements imposed by the camera structure, and the precision of both the wavefront reconstruction and the tracking. We find that a single design can accommodate two guide sensors and one split-plane wavefront sensor integrated into the four corner locations in the camera. © 2010 SPIE.

Abstract:

We present results of a search for anomalous production of two photons together with an electron, muon, τ lepton, missing transverse energy, or jets using pp̄ collision data from 1.1-2.0fb-1 of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs of new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy. © 2010 The American Physical Society.

Abstract:

We present results of a signature-based search for new physics using a dijet plus missing transverse energy (E(T)) data sample collected in 2  fb⁻¹ of pp collisions at √s=1.96  TeV with the CDF II detector at the Fermilab Tevatron. We observe no significant event excess with respect to the standard model prediction and extract a 95% C.L. upper limit on the cross section times acceptance for a potential contribution from a nonstandard model process. The search is made by using novel, data-driven techniques for estimating backgrounds that are applicable to first searches at the LHC.