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The production of Υ (1S), Υ (2S) and Υ (3S) mesons in proton-proton collisions at the centre-of-mass energy of √ s = 7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb−1 collected at the Large Hadron Collider. The Υ mesons are reconstructed in the decay mode Υ → μ+μ− and the signal yields are extracted from a fit to the(More)
The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at √ s = 7 TeV 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.(More)
An angular analysis of the decay J/ψ → μ+μ− is performed to measure the polarization of prompt J/ψ mesons produced in pp collisions at √ s = 7 TeV. The dataset corresponds to an integrated luminosity of 0.37 fb−1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, pT, and rapidity, y, of the J/ψ meson, in the(More)
The calibration and performance of the oppositeside flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B+ → J/ψK+, B0 → J/ψK∗0 and B0 →D∗−μ+νμ decay modes with 0.37 fb−1 of data collected in pp(More)
A search is presented for long-lived particles with a mass between 25 and 50 GeV/c2 and a lifetime between 1 and 200 ps in a sample of proton–proton collisions at a centre-of-mass energy of √ s = 7 TeV, corresponding to an integrated luminosity of 0.62 fb−1, collected by the LHCb detector. The particles are assumed to be pair-produced by the decay of a(More)
The relative rates of B-meson decays into J/ψ and ψ(2S) mesons are measured for the three decay modes in pp collisions recorded with the LHCb detector. The ratios of branching fractions (B) are measured to be B(B+ →ψ(2S)K+) B(B+ → J/ψK+) = 0.594 ± 0.006(stat)± 0.016(syst)± 0.015(Rψ), B(B0 →ψ(2S)K∗0) B(B0 → J/ψK∗0) = 0.476 ± 0.014(stat)± 0.010(syst)±(More)
Charged particle multiplicities are studied in proton–proton collisions in the forward region at a centre-ofmass energy of √ s = 7 TeVwith data collected by the LHCb detector. The forward spectrometer allows access to a kinematic range of 2.0 < η < 4.8 in pseudorapidity, momenta greater than 2 GeV/c and transverse momenta greater than 0.2 GeV/c. The(More)
The energy flow created in pp collisions at √ s = 7 TeV is studied within the pseudorapidity range 1.9 < η < 4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to(More)
The production of the ηc(1S) state in protonproton collisions is probed via its decay to the pp final state with the LHCb detector, in the rapidity range 2.0 < y < 4.5 and in the meson transverse-momentum range pT > 6.5 GeV/c. The cross-section for prompt production of ηc(1S) mesons relative to the prompt J/ψ crosssection is measured, for the first time, to(More)
The polarisation of prompt ψ(2S) mesons is measured by performing an angular analysis of ψ(2S) → μ+μ− decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum pT and rapidity y in the(More)