# Europhysics Conference on High-Energy Physics 2011

Jul 20 – 27, 2011
Alpes Congrès - Alpexpo
Europe/Paris timezone

### Support

Jul 21, 2011, 6:15 PM
15m
Oisans (Alpes Congrès - Alpexpo)

### Oisans

#### Alpes Congrès - Alpexpo

Parallel session talk Flavour Physics and Fundamental Symmetries

### Speaker

Mrs Marina Artuso

### Description

In a data sample corresponding to ∼36 pb−1 of pp collisions at a centre-of-mass energy sqrt(s) = 7 TeV, we make the first observation of the decay Lambda_b -> Lambda_c+Ds- and measure its branching fraction relative to that of Lambda_b -> Lambda_c+π-. We also present related measurements of B hadron decays. In a data sample corresponding to ∼36 pb−1 of pp collisions at a centre-of-mass energy sqrt(s) = 7 TeV, we observe for the first time the decay Bs -> D0 K∗0. A clear signal of 34.5 ± 6.9 events is obtained with a statistical significance over 9 standard deviations and we measure its branching ratio relative to that of B0 → D0 rho0: B(Bs -> D0K∗0)/B(B0 ->D0 rho0) = 1.39 \pm 0.31 \pm 0.17 \pm 0.18, where the first uncertainty is statistical, the second systematic and the third is due to uncertainty in the hadronisation fraction fd/fs. We report first observations of the Cabibbo-suppressed decays B^{-,0} -> D^{0,-}Kππ, and measure their branching fractions relative to the B^{-,0} → D^{0,-}πππ Cabibbo-favoured modes. The measurements are conducted with the LHCb experiment using 35 pb−1 of data collected at sqrt(s) = 7 TeV. The LHCb experiment is pursuing a broad programme of measurements of $B_S$ and $\Lb$ semileptonic decays, with the goal of identifying exclusive hadronic final states and measuring their form factor shapes. We report first measurements of $B_S \to D_S\mu \nu X$, $B_S\to DK\mu\nu X$, and $\Lambda_b\to \Lambda _c \mu\nu X$ based on the 2010 and early 2011 LHCb data samples.

### Primary author

Dr Gaia Lanfranchi (LNF INFN)

 Slides