Constraints on the photon polarisation in b → sγ transitions using Bs0→ ϕe+e− decays
An angular analysis of the Bs0→ ϕe+e− decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1 at centre-of-mass energies of 7, 8 and 13 TeV. The analysis is performed in the very low dielectron invariant mass-squared region between 0.0009 and 0.2615 GeV2/c4. The longitudinal polarisation fraction of the ϕ meson is measured to be less than 11.5% at 90% confidence level. The ATReCP observable, which is related to the lepton forward-backward asymmetry, is measured to be 0.116 ± 0.155 ± 0.006, where the first uncertainty is statistical and the second systematic. The transverse asymmetries, AT2 and ATImCP, which are sensitive to the virtual photon polarisation, are found to be −0.045 ± 0.235 ± 0.014 and 0.002 ± 0.247 ± 0.016, respectively. The results are consistent with Standard Model predictions.
2-s2.0-105001209771
FOM-Institute of Subatomic Physics - NIKHEF
Faculty of Science, Engineering and Medicine
Universität Zürich, Physik-Institut
Faculty of Science, Engineering and Medicine
University of Liverpool
Syracuse University
Instituto Galego de Física de Altas Enerxías (IGFAE)
University of Bristol
Uppsala Universitet
Université Paris-Saclay
2025-03-01
2025
3
47
REVIEWED
EPFL
Funder | Funding(s) | Grant Number | Grant URL |
MICIU | |||
IFIN-HH | |||
ANR | |||
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