In:
Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2020, No. 12 ( 2020-12)
Abstract:
An angular analysis of the B 0 → 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 GeV 2 , where the rate is dominated by the B 0 → K * 0 γ transition with a virtual photon. The fraction of longitudinal polarisation of the K * 0 meson, F L , is measured to be F L = (4 . 4 ± 2 . 6 ± 1 . 4)%, where the first uncertainty is statistical and the second systematic. The $$ {A}_{\mathrm{T}}^{\mathrm{Re}} $$ A T Re observable, which is related to the lepton forward-backward asymmetry, is measured to be $$ {A}_{\mathrm{T}}^{\mathrm{Re}} $$ A T Re = − 0 . 06 ± 0 . 08 ± 0 . 02. The $$ {A}_{\mathrm{T}}^{(2)} $$ A T 2 and $$ {A}_{\mathrm{T}}^{\mathrm{Im}} $$ A T Im transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be $$ {A}_{\mathrm{T}}^{(2)} $$ A T 2 = 0 . 11 ± 0 . 10 ± 0 . 02 and $$ {A}_{\mathrm{T}}^{\mathrm{Im}} $$ A T Im = 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.
Type of Medium:
Online Resource
ISSN:
1029-8479
DOI:
10.1007/JHEP12(2020)081
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
2027350-2
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