• A
• A
• A
• ABC
• ABC
• ABC
• А
• А
• А
• А
• А
Regular version of the site

## Test of lepton universality with Λ0b→pK−ℓ+ℓ− decays

Journal of High Energy Physics. 2020. Vol. 05. P. 140.

The ratio of branching fractions of the decays Λb0 {\Lambda}_b^0 Λb0​ → pK−^{−}−e+^{+}+e−^{−}− and Λb0 {\Lambda}_b^0 Λb0​ → pK−^{−}−μ+^{+}+μ−^{−}−,RpK−1 {R}_{pK}^{-1} RpK−1​, is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb−1^{−1}−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^{2}2< 6.0 GeV2^{2}2/c4^{4}4 and the pK−^{−}− mass range m(pK−^{−}−) < 2600 MeV/c2^{2}2, 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 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{\Lambda}_b^0Λb0→pK−^{−}−e+^{+}+e−^{−}−.