Measurement of angular parameters from the decay ${\mathrm{B}}^0\to {\mathrm{K}}^{\ast 0}{\mu }^{+}{\mu }^{-}$ in proton-proton collisions at $\sqrt{s}=$ 8 TeV

Angular distributions of the decay $$\mathrm{B}$^0 \to $\mathrm{K}$^{*0} \mu^+ \mu^-$arestudiedusingasampleofproton-protoncollisionsat$\sqrt{s} = $ 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 20.5 fb${}^{-1}$. An angular analysis is performed to determine the $P_1$ and $P_5^{\mathrm{\prime }}$ parameters, where the $P_5^{\mathrm{\prime }}$ parameter is of particular interest because of recent measurements that indicate a potential discrepancy with the standard model predictions. Based on a sample of 1397 signal events, the $P_1$ and $P_5^{\mathrm{\prime }}$ parameters are determined as a function of the dimuon invariant mass squared. The measurements are in agreement with predictions based on the standard model.