The angular distributions and the partial branching fraction of the decay $B^0\to K^{*0}{\mu }^{+}{\mu }^{-}$ are studied by using an integrated luminosity of $0.37{\mathrm{fb}}^{-1}$ of data collected with the LHCb detector. The forward-backward asymmetry of the muons, $A_{\mathrm{FB}}$, the fraction of longitudinal polarization, $F_{\mathrm{L}}$, and the partial branching fraction $d\mathcal{B}/d{q}^2$ are determined as a function of the dimuon invariant mass. The measurements are in good agreement with the standard model predictions and are the most precise to date. In the dimuon invariant mass squared range $1.00–6.00{\mathrm{GeV}}^2/c^4$, the results are $A_{\mathrm{FB}}=-{0.06}_{-0.14}^{+0.13}\pm 0.04$, $F_{\mathrm{L}}=0.55\pm 0.10\pm 0.03$, and $d\mathcal{B}/d{q}^2=(0.42\pm 0.06\pm 0.03)\times {10}^{-7}{c}^4/{\mathrm{GeV}}^2$. In each case, the first error is statistical and the second systematic.

• Received 15 December 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.181806

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© 2012 CERN, for the LHCb Collaboration