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oai:recercat.cat:20.500.14342/32842025-03-11T04:13:37Zcom_2072_482405com_2072_183628col_2072_482415

00925njm 22002777a 4500 dc Badalov, Alexey author Calvo Gómez, Míriam author Camboni, Alessandro author Vilasís Cardona, Xavier author LHCb Collaboration - CERN author 2014-04-22 This Letter presents a study of the flavor-changing neutral current radiative B±→K±π∓π±γ decays performed using data collected in proton-proton collisions with the LHCb detector at 7 and 8 TeV center-of-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±π∓π± final state in the [1.1,1.9]  GeV/c2 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±π∓π± 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. http://hdl.handle.net/20.500.14342/3284 https://doi.org/10.1103/PhysRevLett.112.161801 Gran col·lisionador d'hadrons (França i Suïssa) Partícules (Física nuclear) Protons Col·lisions (Física nuclear) Observation of Photon Polarization in the b→sγ Transition