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

Abstract

An angular analysis of the B[superscript 0] → K[superscript *0]e[superscript +]e[superscript −] decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 fb[superscript −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[superscript 2]) interval between 0.002 and 1.120 GeV[superscript 2]/c[superscript 4]. The angular observables F [subscript L] and A [Re over T] which are related to the K[superscript *0] polarisation and to the lepton forward-backward asymmetry, are measured to be F [subscript L] = 0.16 ± 0.06 ± 0.03 and A [Re over T] = 0.10 ± 0.18 ± 0.05, where the first uncertainty is statistical and the second systematic. The angular observables A [(2) over T] and A [Im over T] which are sensitive to the photon polarisation in this q[superscript 2] range, are found to be A [(2) over T] = − 0.23 ± 0.23 ± 0.05 and A [Im over T] = 0.14 ± 0.22 ± 0.05. The results are consistent with Standard Model predictions.