Amplitude analysis of the decay ${\overline{B}}^0\to K_S^0{\pi }^{+}{\pi }^{-}$ and first observation of the CP asymmetry in ${\overline{B}}^0\to K^{\ast }(892{)}^{-}{\pi }^{+}$

Abstract

The time-integrated Dalitz plot of the three-body hadronic charmless decay ${\overline{B}}^0\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ is studied using a $pp$ collision data sample recorded with the LHCb detector, corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$. The decay amplitude is described with an isobar model. Relative contributions of the isobar amplitudes to the ${\overline{B}}^0\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ decay branching fraction and CP asymmetries of the flavour-specific amplitudes are measured. The CP asymmetry between the conjugate ${\overline{B}}^0\to K^{\ast }(892{)}^{-}{\pi }^{+}$ and ${\overline{B}}^0\to K^{\ast }(892{)}^{+}{\pi }^{-}$ decay rates is determined to be $-0.308\pm 0.062$.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-033.html