Angular analysis of the $B^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$ decay

Abstract

This paper presents the first measurement of the forward-backward asymmetry, $A_{\mathrm{FB}}$, and the flat term, $F_H$, that parameterise the angular distribution of the $B^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$ decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb${}^{-1}$, collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the $J/\psi$ and $\psi (2S)$ narrow charmonium resonances. The Standard Model predictions lie within the obtained $68\%$ confidence level interval in the high-mass and within the $99\%$ interval in the low-mass region.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/5812/ (LHCb public pages)