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Test of lepton universality with $$ {\Lambda}_b^0\to {pK}^{-}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ decays
Name
Aaij2020_Article_TestOfLeptonUniversalityWithΛb.pdf
Description
Published version
Size
743.3 KB
Format
Adobe PDF
Checksum (MD5)
5c133860f256d6a5ef4ca583a5b9e0b1
Date Issued
2020
Journal
Journal of High Energy Physics
Publisher
Springer Science and Business Media LLC
Version
Final published version
Abstract
Abstract
The ratio of branching fractions of the decays $$ {\Lambda}_b^0 $$ Λ b 0 → pK − e + e − and $$ {\Lambda}_b^0 $$ Λ b 0 → pK − μ + μ − , $$ {R}_{pK}^{-1} $$ 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 < q 2 < 6.0 GeV2 /c 4 and the pK − mass range m(pK − ) < 2600 MeV/c 2, the ratio of branching fractions is measured to be $$ {R}_{pK}^{-1}={1.17}_{-0.16}^{+0.18}\pm 0.07 $$ R pK − 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 $$ {\Lambda}_b^0 $$ Λ b 0 → pK − e + e − .
The ratio of branching fractions of the decays $$ {\Lambda}_b^0 $$ Λ b 0 → pK − e + e − and $$ {\Lambda}_b^0 $$ Λ b 0 → pK − μ + μ − , $$ {R}_{pK}^{-1} $$ 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 < q 2 < 6.0 GeV2 /c 4 and the pK − mass range m(pK − ) < 2600 MeV/c 2, the ratio of branching fractions is measured to be $$ {R}_{pK}^{-1}={1.17}_{-0.16}^{+0.18}\pm 0.07 $$ R pK − 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 $$ {\Lambda}_b^0 $$ Λ b 0 → pK − e + e − .
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
10.1007/JHEP05(2020)040
