Test of lepton universality with Λb0→pK−ℓ+ℓ−$$ {\Lambda}_b^0\to {pK}^{-}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ decays
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13130_2020_Article_12977.pdf
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Author(s)
Aaij, R.
Abellán Beteta, C.
Ackernley, T.
Adeva, B.
Adinolfi, M.
Afsharnia, H.
Aidala, C. A
Aiola, S.
Ajaltouni, Z.
Akar, S.
Date Issued
May 11, 2020
Publisher
Springer Berlin Heidelberg
Citation
Journal of High Energy Physics. 2020 May 11;2020(5):40
Version
Final published version
Abstract
Abstract
The ratio of branching fractions of the decays Λb0$$ {\Lambda}_b^0 $$ → pK−e+e− and Λb0$$ {\Lambda}_b^0 $$ → pK−μ+μ−,RpK−1$$ {R}_{pK}^{-1} $$, is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb−1 recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range 0.1 < q2< 6.0 GeV2/c4 and the pK− mass range m(pK−) < 2600 MeV/c2, the ratio of branching fractions is measured to be RpK−1=1.17−0.16+0.18±0.07$$ {R}_{pK}^{-1}={1.17}_{-0.16}^{+0.18}\pm 0.07 $$, where the first uncertainty is statistical and the second systematic. This is the first test of lepton universality with b baryons and the first observation of the decay Λb0$$ {\Lambda}_b^0 $$ → pK−e+e−.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1007/JHEP05(2020)040
