2,346 research outputs found
LHCb trigger system
No full textThe status of the design of the LHCb trigger system is reviewed, with special emphasis on the High Level Trigger evolution
First test-beam results with a prototype of the LHCb vertex detector
No full textThe current design of the LHCb vertex detector (VELO: VErtex LOcator) is described. The use of the VELO detector in the second level trigger and the radiation environment at the LHC influence the choice adopted. A first prototype of the detector has been tested on test beams at CERN, and first preliminary results are presented in this contribution. (4 refs)
Looking for New Physics in b-decays with LHCb
No full textThis article is a short and non-exhaustive summary of the prospects to find New Physics with LHCb as was presented at the HCP conference at Toronto on August 26th 2010.This article is a short and non-exhaustive summary of the prospects to find New Physics with LHCb as was presented at the HCP conference at Toronto on August 26th 2010
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Study of the LHCb trigger performance robustness
No full textSeveral ``Robustness Scenarios'' have been studied with the latest versions of the trigger algorithms, as described in the Trigger TDR~\cite{TDR}. The Level-1 Event Size and Execution Time are particularly sensitive to the event multiplicity. Changing the PYTHIA settings within reasonable values changes the event multiplicity by , hence the uncertainty on the size of the CPUs farm and event building network is of this order of magnitude. In the ``worse case'' scenario, denoted as ``Global Test'' in this note, the trigger performance may be degraded by up to for the hadronic channels
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