Measurement of the $C\mathrm{\P }$ asymmetry in $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ decays

A measurement of the $C\mathrm{\P }$ asymmetry in $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ decays is presented using $pp$ collision data, corresponding to an integrated luminosity of 1.0${fb}^{-1}$, recorded by the LHCb experiment during 2011 at a centre-of-mass energy of 7 TeV. The measurement is performed in seven bins of ${\mu }^{+}{\mu }^{-}$ invariant mass squared in the range $0.05<q^2<22.00\mathrm{G}\mathrm{e}{\mathrm{V}}^2\mathrm{/}{c}^4$, excluding the $J\mathrm{/}\psi$ and $\psi (2S)$ resonance regions. Production and detection asymmetries are corrected for using the $B^{+}\to J\mathrm{/}\psi K^{+}$ decay as a control mode. Averaged over all the bins, the $C\mathrm{\P }$ asymmetry is found to be ${{\cal A}_{C\P} = 0.000\pm 0.033{(stat.)} \pm0.005 {(syst.)} \pm 0.007{}(J/\psi K^+)}$, where the third uncertainty is due to the $C\mathrm{\P }$ asymmetry of the control mode. This is consistent with the Standard Model prediction.