Amplitude analysis of the decay $\overline{B}^0 \to K_{S}^0 π^+ π^-$ and first observation of the CP asymmetry in $\overline{B}^0 \to K^{*}(892)^- π^+$

Abstract

The time-integrated Dalitz plot of the three-body hadronic charmless decay ${\overline{B}^0 \to K_{\mathrm{\scriptscriptstyle S}}^0 π^+ π^-}$ 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 ${\overline{B}^0 \to K_{\mathrm{\scriptscriptstyle S}}^0 π^+ π^-}$ decay branching fraction and CP asymmetries of the flavour-specific amplitudes are measured. The CP asymmetry between the conjugate ${\overline{B}^0 \to K^{*}(892)^{-}π^+}$ and ${\overline{B}^0 \to K^{*}(892)^{+}π^-}$ 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