Improved branching-fraction measurements of $B^0_{(s)} \to K_S^0 h^+ h^{'-}$ decays and first observation of $B^0_{s} \to K_S^0 K^+ K^-$

TL;DR

This study measures branching fractions of specific B meson decays, reports the first observation of B_s0 to K_S0 K+ K-, and provides precise ratios of these decay modes using LHCb data.

Contribution

First observation of B_s0 to K_S0 K+ K- decay and precise measurements of branching fraction ratios of charmless three-body B meson decays.

Findings

First observation of B_s0 to K_S0 K+ K- decay.

Measured branching fraction ratios with high precision.

Quantified uncertainties including statistical, systematic, and hadronisation fraction.

Abstract

This paper presents a study of the charmless three-body decays ${B^0_{(s)} \to K_{\mathrm{S}}^0 h^+ h^{\prime -}}$ (where $h^{(\prime)} = \pi, K$), using a sample of $pp$ collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9\mbox{\,fb}^{-1}$. The decay ${B^0_s \to K_{\mathrm{S}}^0 K^+ K^-}$ is observed for the first time, and the following ratios of branching fractions are measured: \begin{alignat*}{6} &\frac{{\cal B}(B^0 \to K^0_{\mathrm{S}} K^+ K^-)}{{\cal B}(B^0 \to K^0_{\mathrm{S}} \pi^+\pi^-)} &&= 0.578 &&\pm 0.007 &&\pm 0.017\,, &\frac{{\cal B}(B^0 \to K^0_{\mathrm{S}} K^\pm\pi^\mp)}{{\cal B}(B^0 \to K^0_{\mathrm{S}} \pi^+\pi^-)} &&= 0.1363 &&\pm 0.0035 &&\pm 0.0051\,, &\frac{{\cal B}(B^0_s \to K^0_{\mathrm{S}} \pi^+\pi^-)}{{\cal B}(B^0 \to K^0_{\mathrm{S}} \pi^+\pi^-)} &&= 0.269 &&\pm 0.011 &&\pm 0.015 && \pm 0.008\,, &\frac{{\cal B}(B^0_s \to K^0_{\mathrm{S}} K^+ K^-)}{{\cal B}(B^0 \to K^0_{\mathrm{S}} \pi^+\pi^-)} &&= 0.0303 &&\pm 0.0041 &&\pm 0.0025 && \pm 0.0009\,, &\frac{{\cal B}(B^0_s \to K^0_{\mathrm{S}} K^\pm\pi^\mp)}{{\cal B}(B^0 \to K^0_{\mathrm{S}} \pi^+\pi^-)} &&= 1.818 &&\pm 0.021 &&\pm 0.031 && \pm 0.056\,, \end{alignat*} where the uncertainties are statistical, systematic, and due to knowledge of the ratio of hadronisation fractions of the $B^0_s$ and $B^0$ mesons, respectively.