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

TL;DR

This paper analyzes the decay of neutral B mesons into a three-body final state, measuring decay amplitudes and CP asymmetries, and reports the first observation of CP asymmetry in a specific decay channel using LHCb data.

Contribution

It provides the first measurement of CP asymmetry in the decay $ar{B}^0 o K^{*}(892)^- o ar{K}^0 ho^-$, using a Dalitz plot analysis with LHCb data.

Findings

CP asymmetry between conjugate decay rates is -0.308 ± 0.062.

Decay amplitudes and their contributions to the branching fraction are quantified.

First observation of CP asymmetry in $ar{B}^0 o K^{*}(892)^- o ar{K}^0 ho^-$ decay.

Abstract

The time-integrated Dalitz plot of the three-body hadronic charmless decay ${{\overline{B}}^0 \to K_{\mathrm{\scriptscriptstyle S}}^0 \pi^+ \pi^-}$ 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 ${\overline{B}^0 \to K_{\mathrm{\scriptscriptstyle S}}^0 \pi^+ \pi^-}$ decay branching fraction and CP asymmetries of the flavour-specific amplitudes are measured. The CP asymmetry between the conjugate ${\overline{B}^0 \to K^{*}(892)^{-}\pi^+}$ and ${\overline{B}^0 \to K^{*}(892)^{+}\pi^-}$ decay rates is determined to be $-0.308 \pm 0.062$.