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.

Using 20.7 pb −1 of e + e − annihilation data taken at √ s = 3.671 GeV with the CLEO-c detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of |Q 2 | = 13.48 GeV 2 by the reaction e + e − → h + h − . The measurements are the first ever with identified pions and kaons of |Q 2 | > 4 GeV 2 , with the results F π (13.48 GeV 2 ) = 0.075 ± 0.008(stat) ± 0.005(syst) and F K (13.48 GeV 2 ) = 0.063±0.004(stat)±0.001(syst). The result for the proton, assumingGeV 2 ) = 0.014 ± 0.002(stat) ± 0.001(syst), which is in agreement with earlier results.

Using data collected with the CLEO detector operating at the CESR e+e- collider at sqrt[s]=3.97-4.26 GeV, we investigate 15 charmonium decay modes of the psi(4040), psi(4160), and Y(4260) resonances. We confirm, at 11 sigma significance, the BABAR Y(4260)-->pi+pi- J/psi discovery, make the first observation of Y(4260)--> pi(0)pi(0) J/psi (5.1 sigma), and find the first evidence for Y(4260)-->K+K- J/psi(3.7 sigma). We measure e+e- cross sections at sqrt[s]=4.26 GeV as sigma(pi+pi- J/psi)=58(+12)(-10)+/-4 pb, sigma(pi(0)pi(0) J/psi)=23(+12)(-8)+/-1 pb, and sigma(K+K- J/psi)=9(+9)(-5)+/-1 pb, in which the uncertainties are statistical and systematic, respectively. Upper limits are placed on other decay rates from all three resonances.

We have studied semileptonic B decay to the exclusive charmless states π, ρ/ω, η and η using the full 15.5 fb −1 CLEO Υ(4S) sample, with measurements performed in subregions of phase space to minimize dependence on a priori knowledge of the form factors involved. We find total branching fractions B(B 0 → π − + ν) = (1.37 ± 0.15 stat ± 0.11 sys ) × 10 −4 and B(B 0 → ρ − + ν) = (2.93 ± 0.37 stat ± 0.37 sys ) × 10 −4 . We find evidence for B + → η + ν, with B(B + → η + ν) = (2.66 ± ±0.80 stat ± 0.56 sys ) × 10 −4 and 1.20 × 10 −4 < B(B + → η + ν) < 4.46 × 10 −4 (90% CL). We also limit B(B + → η + ν) < 1.01 × 10 −4 (90% CL). By combining our B → π ν information with unquenched lattice calculations, we find |V ub | = (3.6 ± 0.4 stat ± 0.2 sys +0.6 −0.4thy ) × 10 −3 .2

The decay branching fractions of the three narrow Upsilon resonances to mu(+)mu(-) have been measured by analyzing about 4.3 fb(-1) e(+)e(-) data collected with the CLEO III detector. The branching fraction B(Upsilon(1S)-->mu(+)mu(-))=(2.49+/-0.02+/-0.07)% is consistent with the current world average, but B(Upsilon(2S)-->mu(+)mu(-))=(2.03+/-0.03+/-0.08)% and B(Upsilon(3S)-->mu(+)mu(-))=(2.39+/-0.07+/-0.10)% are significantly larger than prior results. These new muonic branching fractions imply a narrower total decay width for the Upsilon(2S) and Upsilon(3S) resonances and lower other branching fractions that rely on these decays in their determination.

We measure the branching ratio of the purely leptonic decay of the D + meson with unprecedented precision as B(D + → µ + ν) = (3.82 ± 0.32 ± 0.09) × 10 −4 , using 818 pb −1 of data taken on the ψ(3770) resonance with the CLEO-c detector at the CESR collider. We use this determination to derive a value for the pseudoscalar decay constant f D + , combining with measurements of the D + lifetime and assuming |V cd | = |V us |. We find f D + = (205.8 ± 8.5 ± 2.5) MeV. The decay rate asymmetry.08 ± 0.08, consistent with no CP violation. We also set 90% confidence level upper limits on B(D + → τ + ν) < 1.2 × 10 −3 and B(D + → e + ν) < 8.8 × 10 −6 .

Using 13.3 fb −1 of e + e − collision data taken in the Υ(1S −4S) region with the CLEO III detector at the CESR collider, a search has been made for the new resonance Y (4260) recently reported by the BaBar Collaboration. The production of Y (4260) in initial state radiation (ISR), and its decay into π + π − J/ψ, are confirmed. A good quality fit to our data is obtained with a single resonance. We determine M (Y (4260)) = (4284 +17 −16 (stat) ± 4(syst)) MeV/c 2 , Γ(Y (4260)) = (73 +39 −25 (stat) ± 5(syst)) MeV/c 2 , and Γ ee (Y (4260)) × B(Y (4260) → π + π − J/ψ) = (8.9 +3.9 −3.1 (stat) ± 1.8(syst)) eV/c 2 .

We use data collected by the CLEO III detector at the Cornell Electron Storage Ring to measure the inclusive yields of D(s) mesons as B(Y(5S) --> D(s)X) = (44-7 +/- 4.2 +/- 9.9)% and B(Y(4S) --> D(s)X) = (18.1 +/- 0.5 +/- 2.8)%. From these measurements, we make a model dependent estimate of the ratio of B(s)*B(s)* to the total bb quark pair production of (16.0 +/- 2.6 +/- 5.8)% at the Y(5S) energy.