Angular analysis of the B 0 → K * 0 e + e − decay in the low- q 2 region

An angular analysis of the B 0 → K * 0 e + 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 ( q 2 ) interval between 0.002 and 1.120 GeV 2 /c 4 . The angular observables F L and A T Re which are related to the K * 0 polarisation and to the lepton forward-backward asymmetry, are measured to be F L = 0 . 16 ± 0 . 06 ± 0 . 03 and A T Re  = 0.10 ± 0.18 ± 0.05, where the first uncertainty is statistical and the second systematic. The angular observables A T (2) and A T Im which are sensitive to the photon polarisation in this q 2 range, are found to be A T (2)  = − 0.23 ± 0.23 ± 0.05 and A T Im  = 0.14 ± 0.22 ± 0.05. The results are consistent with Standard Model predictions.