Bayesian analysis of $b\to s{\mu }^{+}{\mu }^{-}$ Wilson coefficients using the full angular distribution of ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ decays

Abstract

Following updated and extended measurements of the full angular distribution of the decay ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ by the LHCb collaborations, as well as a new measurement of the $\Lambda \to p{\pi }^{-}$ decay asymmetry parameter by the BESIII collaboration, we study the impact of these results on searches for non-standard effects in exclusive $b\to s{\mu }^{+}{\mu }^{-}$ decays. To this end, we constrain the Wilson coefficients ${\mathcal{C}}_9$ and ${\mathcal{C}}_{10}$ of the numerically leading dimension-six operators in the weak effective Hamiltonian, in addition to the relevant nuisance parameters. In stark contrast to previous analyses of this decay mode, the changes in the updated experimental results lead us to find very good compatibility with both the Standard Model and with the $b\to s{\mu }^{+}{\mu }^{-}$ anomalies observed in rare $B$-meson decays. We provide a detailed analysis of the impact of the partial angular distribution, the full angular distribution, and the ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ branching fraction on the Wilson coefficients. In this process, we are also able to constrain the size of the production polarization of the ${\Lambda }_b$ baryon at LHCb.

6 pages, 4 figures, 2 tables

References in corpus (6)

• B-physics anomalies: a guide to combined explanations
• Probing New Physics via the $B_s^0\to {\mu }^{+}{\mu }^{-}$ Effective Lifetime
• Multichannel one-to-two transition amplitudes in a finite volume
• Study of the kinematic dependences of ${\Lambda }_b^0$ production in $pp$ collisions and a measurement of the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\pi }^{-}$ branching fraction
• Angular distribution of polarised ${\Lambda }_b$ baryons decaying to $\Lambda {\ell }^{+}{\ell }^{-}$
• Angular distribution of the rare decay ${\Lambda }_b\to \Lambda (\to N\pi ){\ell }^{+}{\ell }^{-}$