Journal of High Energy Physics > 2017 > 2017 > 6 > 1-17
Observation of the decay Λ b0 → pK−μ+μ− and a search for CP violation
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Abstract
A search for CP violation in the decay Λ b0 → pK−μ+μ− is presented. This decay is mediated by flavour-changing neutral-current transitions in the Standard Model and is potentially sensitive to new sources of CP violation. The study is based on a data sample of proton-proton collisions recorded with the LHCb experiment, corresponding to an integrated luminosity of 3 fb−1. The Λ b0 → pK−μ+μ− decay is observed for the first time, and two observables that are sensitive to different manifestations of CP violation are measured, Δ A C P ≡ A C P Λ b 0 → p K − μ + μ − − A C P Λ b 0 → p K − J / ψ $$ \Delta {\mathcal{A}}_{CP}\equiv {\mathcal{A}}_{CP}\left({\Lambda}_b^0\to p{K}^{-}{\mu}^{+}{\mu}^{-}\right)-{\mathcal{A}}_{CP}\left({\Lambda}_b^0\to p{K}^{-}J/\psi \right) $$ and a a C P T ^ ‐ odd $$ {a}_{CP}^{\widehat{T}\hbox{-} odd} $$ , where the latter is based on asymmetries in the angle between the μ+μ− and pK− decay planes.
These are measured to be Δ A C P = − 3.5 ± 5.0 stat ± 0.2 syst × 10 − 2 , a C P T ^ ‐ odd = 1.2 ± 5.0 stat ± 0.7 syst × 10 − 2 , $$ \begin{array}{l}\Delta {\mathcal{A}}_{CP}=\left(-3.5\pm 5.0\left(\mathrm{stat}\right)\pm 0.2\left(\mathrm{syst}\right)\right)\times {10}^{-2},\hfill \\ {}{a}_{CP}^{\widehat{T}\hbox{-} odd}=\left(1.2\pm 5.0\left(\mathrm{stat}\right)\pm 0.7\left(\mathrm{syst}\right)\right)\times {10}^{-2},\hfill \end{array} $$
and no evidence for CP violation is found.
Identifiers
journal e-ISSN : | 1029-8479 |
DOI | 10.1007/JHEP06(2017)108 |