The polarisation of prompt [Formula: see text] mesons is measured by performing an angular analysis of [Formula: see text] decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0[Formula: see text], collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum [Formula: see text] and rapidity [Formula: see text] in the kinematic region [Formula: see text] and [Formula: see text], and is compared to theoretical models. No significant polarisation is observed.

The decay B0→ψ(2S)K+π- is analyzed using 3 fb-1 of pp collision data collected with the LHCb detector. A model-independent description of the ψ(2S)π mass spectrum is obtained, using as input the Kπ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the ψ(2S)π mass spectrum can be described in terms of Kπ reflections alone is rejected with more than 8σ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430)- exotic state.

Using a data sample of pp collisions corresponding to an integrated luminosity of 3 fb^-1, the Ξb- and Ωb- baryons are reconstructed in the Ξb-→J/ψΞ- and Ωb-→J/ψΩ- decay modes and their lifetimes measured to beτ(Ξb-)=1.55-0.09+0.10(stat)±0.03(syst)ps,τ(Ωb-)=1.54-0.21+0.26(stat)±0.05(syst)ps. These are the most precise determinations to date. Both measurements are in good agreement with previous experimental results and with theoretical predictions. © 2014 The Authors.

Bose-Einstein correlations of same-sign charged pions, produced in proton-proton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decrease.

Long-lived particles decaying to e±μ∓ν, with masses between 7 and 50GeV/c2 and lifetimes between 2 and 50ps, are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using 5.4fb-1 of pp collisions collected with the LHCb detector at a centre-of-mass energy of s=13TeV. Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of 125GeV/c2, and the charged current production from an on-shell W boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes.