LHCb

Abstract:

Using 355pb-1 of data collected by the CDF II detector in pp̄ collisions at s=1.96TeV at the Fermilab Tevatron, we study the fully reconstructed hadronic decays B(s)0→D(s)-π+ and B(s)0→D(s)- π+π+π-. We present the first measurement of the ratio of branching fractions B(Bs0→Ds-π+π+π-)/B(B0→D-π+π+π-)=1. 05±0.10(stat)±0.22(syst). We also update our measurement of B(Bs0→Ds-π+)/B(B0→D-π+) to 1.13±0.08(stat)±0. 23(syst), improving the statistical uncertainty by more than a factor of 2. We find B(Bs0→Ds-π+)=[3.8±0.3(stat)±1.3(syst)]×10-3 and B(Bs0→Ds-π+π+π-)=[8.4±0.8(stat)±3.2(syst)] ×10-3. © 2007 The American Physical Society.

Abstract:

We present a measurement of the branching fraction and time-dependent CP asymmetry of B0→ρ0K0. The results are obtained from a data sample of 227×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at Stanford Linear Accelerator Center. From a time-dependent maximum likelihood fit yielding 111±19 signal events, we find B(B0→ρ0K0)=(4.9±0.8±0.9)×10-6, where the first error is statistical and the second systematic. We report the measurement of the CP parameters Sρ0KS0=0.20±0.52±0.24 and Cρ0KS0=0.64±0.41±0.20. © 2007 The American Physical Society.

Abstract:

We present an observation of B→η′K*. The data sample corresponds to 232×106 BB̄ pairs collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. We measure the branching fractions (in units of 10-6) B(B0→η′K*0)=3.8±1.1±0.5 and B(B+→η′K*+)=4.9-1.7+1.9±0.8, where the first error is statistical and the second systematic. A simultaneous fit results in the observation of B→η′K* with B(B→η′K*)= 4.1-0.9+1.0±0.5. We also search for B→η′ρ and η′f0(980)(f0→π+π-) with results and 90% confidence level upper limits B(B+→η′ρ+)=8.7-2.8-1.3+3.1+2.3 (<14), B(B0→η′ρ0)<3.7, and B(B0→η′f0(980) (f0→π+π-))<1.5. Charge asymmetries in the channels with significant yields are consistent with zero. © 2007 The American Physical Society.

Abstract:

We present a new measurement of the B+ meson differential cross section dσ/dpT at s=1960GeV. The data correspond to an integrated luminosity of 739pb-1 collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. B+ candidates are reconstructed through the decay B+→J/ψK+, with J/ψ→μ+μ-. The integrated cross section for producing B+ mesons with pT≥6GeV/c and |y|≤1 is measured to be 2.78±0.24μb. © 2007 The American Physical Society.

Abstract:

The design, manufacture and testing of lightweight glass-coated beryllium spherical converging mirrors for the RICH1 detector of the LHCb experiment are described. The mirrors need to be lightweight to minimize the material budget and fluorocarbon-compatible to avoid degradation in the RICH1 C4F10 gas radiator. Results of the optical measurements for small-sized prototypes and for a full-sized prototype mirror are reported. © 2006 Elsevier B.V. All rights reserved.