Angular analysis of the B0 → K*0e+e− decay in the low-q2 region

Abstract

An angular analysis of the B0 → K*0e+e− decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV during 2011 and 2012. For the first time several observables are measured in the dielectron mass squared (q2) interval between 0.002 and 1.120 GeV2/c4. The angular observables FL and A ReT which are related to the K*0 polarisation and to the lepton forward-backward asymmetry, are measured to be FL = 0.16 ± 0.06 ± 0.03 and A ReT = 0.10 ± 0.18 ± 0.05, where the first uncertainty is statistical and the second systematic. The angular observables A (2)T and A ImT which are sensitive to the photon polarisation in this q2 range, are found to be A (2)T = − 0.23 ± 0.23 ± 0.05 and A ImT = 0.14 ± 0.22 ± 0.05. The results are consistent with Standard Model predictions.