Guy Wilkinson

Abstract:

Large detector systems for particle and astroparticle physics; Particle tracking detectors; Gaseous detectors; Calorimeters; Cherenkov detectors; Particle identification methods; Photon detectors for UV. visible and IR photons; Detector alignment and calibration methods; Detector cooling and thermo-stabilization; Detector design and construction technologies and materials. The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems. as established by test beam measurements and simulation studies. is described. © 2008 IOP Publishing Ltd and SISSA.

Abstract:

Using a data sample of 24.5×106 ψ(2S) the reactions ψ(2S)→γχcJ, χcJ→γγ have been studied for the first time to determine the two-photon widths of the χcJ states of charmonium in their decay into two photons. The measured quantities are B(ψ(2S)→γχc0)×B(χc0→γγ)=(2. 17±0.32±0.10)×10-5 and B(ψ(2S)→γχc2) ×B(χc2→γγ)=(2.68±0.28±0.15)×10-5. Using values for B(ψ(2S)→γχc0,c2) and Γ(χc0,c2) from the literature the two-photon widths are derived to be Γγ γ(χc0)=(2.36±0.35±0.22)keV, Γγγ(χ c2)=(0.66±0.07±0.06)keV, and R≡Γγγ(χ c2)/Γγγ(χc0)=0.278±0.050±0.036. The importance of the measurement of R is emphasized. For the forbidden transition, χc1→γγ, an upper limit of Γγγ(χc1) <0.03keV is established. © 2008 The American Physical Society.

Abstract:

Using Υ(2S) and Υ(3S) data collected with the CLEO III detector we have searched for decays of χbJ to final states with open charm. We fully reconstruct D0 mesons with pD0>2.5GeV/c in three decay modes (K-π+, K-π+π0, and K-π-π+π+) in coincidence with radiative transition photons that tag the production of one of the χbJ(nP) states. Significant signals are obtained for the two J=1 states. Recent nonrelativistic QCD (NRQCD) calculations of χbJ(nP)→cc̄X depend on one nonperturbative parameter per χbJ triplet. The extrapolation from the observed D0X rate over a limited momentum range to a full cc̄X rate also depends on these same parameters. Using our data to fit for these parameters, we extract results which agree well with NRQCD predictions, confirming the expectation that charm production is largest for the J=1 states. In particular, for J=1, our results are consistent with cc̄g accounting for about one-quarter of all hadronic decays. © 2008 The American Physical Society.

Abstract:

Analyzing Y(nS) decays acquired with the CLEO detector operating at the CESR e+e- collider, we measure for the first time the product branching fractions B[Y(nS)→YX bJ((n-1)P)]B[X bJ(n-1)P)→Xi] for n=2 and 3, where Xi denotes, for each i, one of the 14 exclusive light-hadron final states for which we observe significant signals in both X bJ(1P) and X bJ(2P) decays. We also determine upper limits for the electric dipole (E1) transitions Y(3S)→YX bJ(1P). © 2008 The American Physical Society.

Abstract:

We report the first observation of Υ(2S)→ηΥ(1S), with a branching fraction B=(2.1-0.6+0.7(stat)±0.3(syst))×10-4 and a statistical significance 5.3σ. Data were acquired with the CLEO III detector at the CESR e+e- symmetric collider. This is the first process observed involving a b-quark spin flip. For related transitions, 90% confidence limits in units of 10-4 are B(Υ(2S)→π0Υ(1S))<1.8, B(Υ(3S)→ηΥ(1S))<1.8, B(Υ(3S)→π0Υ(1S)) <0.7, and B(Υ(3S)→π0Υ(2S))<5.1. © 2008 The American Physical Society.