LHCb CollaborationAlfonso Albero, AlejandroGarrido Beltrán, LluísGascón Fora, DavidGraciani Díaz, RicardoGraugés Pous, EugeniMarin Benito, Carla2022-05-102022-05-1020201126-6708https://hdl.handle.net/2445/185475An angular analysis of the B0 → K∗0 e +e − decay is performed using a data sample corresponding to an integrated luminosity of 9 fb−1 of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared (q 2 ) interval between 0.0008 and 0.257 GeV2 , where the rate is dominated by the B0 → K∗0γ transition with a virtual photon. The fraction of longitudinal polarisation of the K∗0 meson, FL, is measured to be FL = (4.4 ± 2.6 ± 1.4)%, where the first uncertainty is statistical and the second systematic. The ARe T observable, which is related to the lepton forward-backward asymmetry, is measured to be ARe T = −0.06 ± 0.08 ± 0.02. The A (2) T and AIm T transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be A (2) T = 0.11 ± 0.10 ± 0.02 and AIm T = 0.02 ± 0.10 ± 0.01. The results are consistent with Standard Model predictions and provide the world's best constraint on the b → sγ photon polarisation.25 p.application/pdfengcc-by (c) LHCb Collaboration (UB: Garrido, L. et al., 2020https://creativecommons.org/licenses/by/4.0/HadronsGran Col·lisionador d'HadronsFísica de partículesExperimentsHadronsLarge Hadron Collider (France and Switzerland)Particle physicsExperimentsinfo:eu-repo/semantics/article7104942022-05-10info:eu-repo/semantics/openAccess