Measurement of cp violation in the phase space of B ^±→K^±π⁺π^- and B^±→K^±K⁺K^- Decays

The charmless decays B ^±→K ^±π ⁺π ^- and B ^±→K ^±K ⁺K ^- are reconstructed using data, corresponding to an integrated luminosity of 1.0 fb ^-1, collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured as A _CP(B ^±→K ^±π ⁺π ^-)=0.032±0.008 (stat)±0.004 (syst)±0.007(J/ψK ^±) and A _CP(B ^±→K ^±K ⁺K ^-)=-0. 043±0.009 (stat)±0.003 (syst)±0.007(J/ψK ^±), where the third uncertainty is due to the CP asymmetry of the B ^±→J/ψK ^± reference mode. The significance of A _CP(B ^±→K ^±K ⁺K ^-) exceeds three standard deviations and is the first evidence of an inclusive CP asymmetry in charmless three-body B decays. In addition to the inclusive CP asymmetries, larger asymmetries are observed in localized regions of phase space.