Guy Wilkinson

Abstract:

We report the first determination of the relative strong-phase difference between D0→KS,L0K+K- and D⊃̄0→KS, L0K+K-. In addition, we present updated measurements of the relative strong-phase difference between D0→KS, L0π+π- and D⊃̄0→KS,L0π +π-. Both measurements exploit the quantum coherence between a pair of D0 and D⊃̄0 mesons produced from ψ(3770) decays. The strong-phase differences measured are important for determining the Cabibbo-Kobayashi-Maskawa angle γ/Φ3 in B -→K-D⊃0 decays, where D⊃0 is a D0 or D⊃̄0 meson decaying to KS0h+h- (h=π, K), in a manner independent of the model assumed to describe the D0→KS0h +h- decay. Using our results, the uncertainty in γ/Φ3 due to the error on the strong-phase difference is expected to be between 1.7° and 3.9° for an analysis using B -→K-D⊃0, D⊃0→KS0π+π - decays, and between 3.2° and 3.9° for an analysis based on B-→K-D⊃0, D⊃0→KS0K+K - decays. A measurement is also presented of the CP-odd fraction, F-, of the decay D0→KS0K+K- in the region of the Φ→K+K- resonance. We find that in a region within 0.01GeV2/c4 of the nominal Φ mass squared F->0.91 at the 90% confidence level. © 2010 The American Physical Society.

Abstract:

We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D+ and Ds+ mesons to final states of the form h±e e+, where h is either π or K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818pb-1 at the center-of-mass energy E CM=3.774GeV containing 2.4×106 D+D- pairs and 602pb-1 at ECM=4.170GeV containing 0.6×106 Ds*±Ds pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D +→π+e+e-)<5. 9×10-6, B(D+→π-e +e+)<1.1×10-6, B(D+→ K+e+e-)<3.0×10-6, B(D +→K-e+e+)<3.5×10 -6, B(Ds+→π+e+e-)<2. 2×10-5, B(Ds+→π-e+e +)<1.8×10-5, B(Ds+→K+e +e-)<5.2×10-5, and B(Ds+→K -e+e+)<1.7×10-5. © 2010 The American Physical Society.

Abstract:

Decays of b hadrons into final states containing a D0 meson and a muon are used to measure the bb̄ production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2<η<6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b̄-flavoured hadrons is (75.3±5.4±13.0) μb. © 2010 CERN.

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.