Angular moments of the decay $Lambda_b^0 rightarrow Lambda mu^{+} mu^{-}$ at low hadronic recoil

An analysis of the angular distribution of the decay $Lambda_b^0 rightarrow Lambda mu^{+} mu^{-}$ is presented, using data collected with the LHCb detector between 2011 and 2016 and corresponding to an integrated luminosity of approximately $5,fb^{-1}$. Angular observables are determined using a moment analysis of the angular distribution at low hadronic recoil, corresponding to the dimuon invariant mass squared range $15 < q^{2} < 20, GeV^2/c^4$. The full basis of observables is measured for the first time. The lepton-side, hadron-side and combined forward-backward asymmetries of the decay are determined to be begin{align} A_{FB}^{l} & = -0.39 pm 0.04,rm{stat} pm 0.01, rm{syst}, onumber A_{FB}^{h} & = -0.30 pm 0.05,rm{stat} pm 0.02, rm{syst}, onumber A_{FB}^{lh} & = +0.25 pm 0.04,rm{stat} pm 0.01, rm{syst}. onumber end{align} The measurements are consistent with Standard Model predictions.