Branching ratios of charmed baryons in the LHCb experiment

[摘要] LHCb is the dedicated heavy flavour experiment on the LHC accelerator ring. An analysis measuring the relative branching fractions of Lc->phh decays is presented using 1 inverse femtobarn of proton - proton collisions gathered by LHCb during 2011.Independent measurements are made using samples of Lc produced from the primary interaction and from those produced in semileptonic decays of Lb baryons.The measured relative branching ratios in the prompt analysis areB(Lc->pK-K+)/B(Lc->pK-pi+) = (2.03 ± 0.07 (stat) ± 0.10 (syst)) × 10−2, andB(Lc->ppi-pi+)/B(Lc->pK-pi+) = (7.04±0.19(stat)±0.34(syst))×10−2,while in the semileptonic analysis they are measured to beB(Lc->pK-K+)/B(Lc->pK-pi+) = (1.68 ± 0.03 (stat) ± 0.04 (syst)) × 10−2, andB(Lc->ppi-pi+)/B(Lc->pK-pi+) = (7.45±0.06(stat)±0.24(syst))×10−2.In the semileptonic analysis we make the first observation of the decay mode Lc->pK+pi- with a significance of 11.1 sigma. We measure the ratio:B(Lc->pK+pi-)/B(Lc->pK-pi+) = (1.62±0.15(stat)±0.05(syst))×10−3.Charged hadron discrimination in LHCb is provided by two ring imaging Cherenkov detectors. A data-driven study on the performance of the aerogel Cherenkov radiator is presented. Particle identification information is used to construct variables describing the likelihood of hadronic particle hypotheses of reconstructed tracks, on which cuts are placed in typical physics analyses. The preparation of new data samples allowing for the data-driven efficiency correction of particle identification cuts on proton tracks is described.

[发布机构] University:University of Glasgow;Department:School of Physics and Astronomy

[关键词] particle physics, charmed baryons, LHCb, RICH, Lc->phh