We present a measurement of formfactor independent angular observables in the decay $B^0\to K^{*}(892)^{0}\mu^+ \mu^$. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0fb$^{1}$, collected by the LHCb experiment in $pp$ collisions at a centerofmass energy of 7TeV. Four observables are measured in six bins of the dimuon invariant mass squared, $q^2$, in the range $0.1<q^2<19.0$GeV$^{2}$/c$^{4}$. Agreement with Standard Model predictions is found for 23 of the 24 measurements. A local discrepancy, corresponding to $3.7$ Gaussian standard deviations, is observed in one $q^2$ bin for one of the observables. Considering the 24 measurements as independent, the probability to observe such a discrepancy, or larger, in one is $0.5\%$.
Measured values of $P_{4}^{\prime}$ and $P_5^{\prime}$ (black points) compared with SM predictions from Ref. \cite{DescotesGenon:2013vna} (blue bands). 
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Animated gif made out of all figures. 
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Measurement of the observables $P_{4,5,6,8}^{\prime}$ and $S_{4,5,7,8}$ in the six $q^2$ bins of the analysis. For the observables $P_i^{\prime}$ the measurement in the $q^2$bin $1.0<q^2<6.0$ $ {\mathrm{ Ge V^2 /}c^4}$ , which is the theoretically preferred region at large recoil, is also reported. The first uncertainty is statistical and the second is systematic. 
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Created on 21 October 2019.