This Letter presents a study of the flavor-changing neutral current radiative B AE → K AE π ∓ π AE γ decays performed using data collected in proton-proton collisions with the LHCb detector at 7 and 8 TeV centerof-mass energies. In this sample, corresponding to an integrated luminosity of 3 fb −1 , nearly 14 000 signal events are reconstructed and selected, containing all possible intermediate resonances with a K AE π ∓ π AE final state in the ½1.1; 1.9 GeV=c 2 mass range. The distribution of the angle of the photon direction with respect to the plane defined by the final-state hadrons in their rest frame is studied in intervals of K AE π ∓ π AE mass and the asymmetry between the number of signal events found on each side of the plane is obtained. The first direct observation of the photon polarization in the b → sγ transition is reported with a significance of 5.2σ.
An angular analysis of the decay B 0 → φK * (892) 0 is reported based on a pp collision data sample, corresponding to an integrated luminosity of 1.0 fb −1 , collected at a centre-of-mass energy of √ s = 7 TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave K + π − and K + K − contributions are taken into account and found to be significant. A comparison of the B 0 → φK * (892) 0 and B 0 → φK * (892) 0 results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
Evidence is presented for the decay B + c → J/ψ 3π + 2π − using proton-proton collision data, corresponding to an integrated luminosity of 3 fb −1 , collected with the LHCb detector. A signal yield of 32 ± 8 decays is found with a significance of 4.5 standard deviations. The ratio of the branching fraction of the B + c → J/ψ 3π + 2π − decay to that of the B + c → J/ψ π + decay is measured to be B (B + c → J/ψ 3π + 2π −) B B + c → J/ψ π + = 1.74 ± 0.44 ± 0.24, where the first uncertainty is statistical and the second is systematic.
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