Test of lepton universality with Λ b 0 → pK − ℓ + ℓ − decays

Journal article

The ratio of branching fractions of the decays Λb0 → pK−e+e− and Λb0 → pK−μ+μ−, RpK−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, 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 → pK−e+e−.

Authors: Aaij, R; Abellán Beteta, C; Ackernley, T; Adeva, B; Adinolfi, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Journal of High Energy Physics
• Volume: 2020
• Issue: 5
• Article number: 40
• Publication date: 2020-05-11
• Acceptance date: 2020-04-10
• DOI: 10.1007/jhep05(2020)040
• EISSN: 1029-8479
• ISSN: 1126-6708
• Language: English
• Keywords: Branching fraction; Hadron- Hadron scattering (experiments); B physics; Flavour Changing Neutral Currents; Rare decay