Evidence for $C\!P$ violation in $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to K^{\pm}K^+K^-$ decays

The charmless three-body decays $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to K^{\pm}K^+K^-$ are reconstructed in 1.0 fb$^{-1}$ of data collected by LHCb in 2011. Both samples include charmonium contributions decaying to $\pi^+\pi^-$ and $K^+K^-$, except the decay $B^{\pm}\to J/\psi(\pi^+\pi^-) K^{\pm}$, which was removed to veto $J/\psi\to\mu^+\mu^-$. The inclusive charge asymmetries of these modes are measured, using $B^{\pm}\to J/\psi K^{\pm}$ as a control channel. The asymmetries are \begin{eqnarray} A_{C\!P}(B^{\pm}\to K^{\pm}\pi^+\pi^-) = +0.034 \pm 0.009{\rm{(stat)}} \pm 0.004{\rm{(syst)}} \pm 0.007(J/\psi K^{\pm}) \, , \nonumber \\ A_{C\!P}(B^{\pm}\to K^{\pm}K^+K^-) = -0.046 \pm 0.009{\rm{(stat)}} \pm 0.005{\rm{(syst)}} \pm 0.007(J/\psi K^{\pm}) \, , \nonumber \end{eqnarray} where the first uncertainty is statistical, the second systematic, and the third comes from the PDG value of $A_{C\!P}(B^{\pm}\to J/\psi K^{\pm})$. The charge asymmetries of $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to K^{\pm}K^+K^-$ have significances of 2.8 and 3.7 standard deviations, respectively. The latter is the first evidence of inclusive $C\!P$ asymmetry in charmless three-body $B$ decays.