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

Abstract

An angular analysis of the B0 → 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 GeV2/c4 . The angular observables FL and ARe T 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 ARe T = 0.10±0.18±0.05, where the first uncertainty is statistical and the second systematic. The angular observables A (2) T and AIm T which are sensitive to the photon polarisation in this q 2 range, are found to be A (2) T = −0.23 ± 0.23 ± 0.05 and AIm T = 0.14 ± 0.22 ± 0.05. The results are consistent with Standard Model predictions.