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Using Λb→Λμ+μ− data within a Bayesian analysis of |ΔB|=|ΔS|=1 decays

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Meinel Stefan, van Dyk Danny,
Project Rare decays of B-mesons and the physics of the early Universe
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Original article (peer-reviewed)

Journal Physical Review D
Volume (Issue) 94(1)
Page(s) 013007
Title of proceedings Physical Review D
DOI 10.1103/physrevd.94.013007

Open Access

Type of Open Access Website


We study the impact of including the baryonic decay Λb→Λ(→pπ-)μ+μ- in a Bayesian analysis of |ΔB|=|ΔS|=1 transitions. We perform fits of the Wilson coefficients C9, C9′, C10 and C10′, in addition to the relevant nuisance parameters. Our analysis combines data for the differential branching fraction and three angular observables of Λb→Λ(→pπ-)μ+μ- with data for the branching ratios of Bs→μ+μ- and inclusive b→sℓ+ℓ- decays. Newly available precise lattice QCD results for the full set of Λb→Λ form factors are used to evaluate the observables of the baryonic decay. Our fits prefer shifts to C9 that are opposite in sign compared to those found in global fits of only mesonic decays, and the posterior odds show no evidence of physics beyond the Standard Model. We investigate a possible hadronic origin of the observed tensions between theory and experiment.