O. Callot

The LHCb trigger and its performance in 2011

The LHCb trigger and its performance based on data taken at the LHC in 2011 is presented. LHCb is designed to perform flavour physics measurements, and its trigger distinguishes charm and beauty decays from the light quark background. It uses a combination of lepton identification of particles, transverse momentum of particles and selects particles originating from hadrons which decay after a finite flight distance. The trigger reduces the

Differential branching fraction and angular analysis of the B +→ K+μ+μ- decay

\sim 11

Measurement of ψ(2S) meson production in pp collisions at √s = 7 TeV

MHz of bunch-bunch crossings with at least one non-elastic pp-interaction to 3 kHz of events which are written to storage in two trigger levels. The first level is implemented in hardware, while the next level is a software application which runs on all processors of a large computer farm. A data driven method is used to evaluate the performance of the trigger for several charm and beauty decay modes.

Measurement of B meson production cross-sections in proton-proton collisions at \( \sqrt{s}=7 \) TeV

A bstractThe angular distribution and differential branching fraction of the decay B+→ K+μ+μ− are studied with a dataset corresponding to 1.0fb−1 of integrated luminosity, collected by the LHCb experiment. The angular distribution is measured in bins of dimuon invariant mass squared and found to be consistent with Standard Model expectations. Integrating the differential branching fraction over the full dimuon invariant mass range yields a total branching fraction of

Differential branching fraction and angular analysis of the decay B-0 -> K*(0)mu(+)mu(-)

\mathcal{B}

Measurement of relative branching fractions of B decays to psi(2S) and J/psi mesons

(B+ → K+μ+μ−) = (4.36 ± 0.15 ± 0.18) × 10−7. These measurements are the most precise to date of the B+ → K+μ+μ− decay.

Study of

The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

D_{sJ}

\sqrt{s}=7\ \mbox{TeV}

decays to

\end{document} has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb−1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S)→μ+μ− and ψ(2S)→J/ψπ+π−, with the J/ψ meson decaying into two muons. Results are presented both for promptly produced ψ(2S) mesons and for those originating from b-hadron decays. In the kinematic range pT(ψ(2S))≤16 GeV/c and 2<y(ψ(2S))≤4.5 we measure where the last uncertainty on the prompt cross-section is due to the unknown ψ(2S) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb J/ψ measurements we determine the inclusive branching fraction where the last uncertainty is due to the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

D^+\KS

\mathcal{B}(b \rightarrow J/\psi X)