# name
Strong constraints on the b → sγ photon polarisation from B 0 → K *0 e + e − decays

# metadata.dc.description.abstract[].value
An 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.

# metadata.dc.relation.ispartof[].value
Journal of High Energy Physics, 2020, vol. 8, num. 3, p. 1-25

# metadata.dc.rights[].value
cc-by (c) LHCb Collaboration (UB: Garrido, L. et al., 2020

# metadata.dc.source[].value
Articles publicats en revistes (Física Quàntica i Astrofísica)

# metadata.dc.subject.other[].value
Large Hadron Collider (France and Switzerland)

# metadata.dc.title[].value
Strong constraints on the b → sγ photon polarisation from B 0 → K *0 e + e − decays