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 GeV^2, where the rate is dominated by the B0 → K*0 γ 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 A_T^Re observable, which is related to the lepton forward-backward asymmetry, is measured to be A_T^Re = −0.06 ± 0.08 ± 0.02. The A_T^(2) and A_T^Im transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be A_T^(2) = 0.11 ± 0.10 ± 0.02 and 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 → s γ photon polarisation.

Aaij, R., Abellán Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2020). Strong Constraints on the b → s γ Photon Polarisation from B0 → K*0 e+ e− Decays. JOURNAL OF HIGH ENERGY PHYSICS, 2020(12), 0-24 [10.1007/JHEP12(2020)081].

Strong Constraints on the b → s γ Photon Polarisation from B0 → K*0 e+ e− Decays

Betti, F.;Capriotti, L.;Carbone, A.;Ferrari, F.;Galli, D.;Maccolini, S.;Manuzzi, D.;Patrignani, C.;Pisani, F.;Zucchelli, S.;
2020

Abstract

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 GeV^2, where the rate is dominated by the B0 → K*0 γ 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 A_T^Re observable, which is related to the lepton forward-backward asymmetry, is measured to be A_T^Re = −0.06 ± 0.08 ± 0.02. The A_T^(2) and A_T^Im transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be A_T^(2) = 0.11 ± 0.10 ± 0.02 and 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 → s γ photon polarisation.
2020
Aaij, R., Abellán Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2020). Strong Constraints on the b → s γ Photon Polarisation from B0 → K*0 e+ e− Decays. JOURNAL OF HIGH ENERGY PHYSICS, 2020(12), 0-24 [10.1007/JHEP12(2020)081].
Aaij, R.; Abellán Beteta, C.; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Aidala, C.A.; Aiola, S.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; A...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/797699
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