Measurement of the CKM angle $\gamma$ in $B^{\pm} \rightarrow D(\rightarrow K^{0}_{\rm S} h^{\prime+}h^{\prime-})h^{\pm}$ decays with a novel approach

TL;DR

This paper presents a novel, model-independent measurement of the CKM angle gamma using B meson decays, combining data from BESIII and LHCb to achieve the most precise single measurement to date.

Contribution

The study introduces a new approach that combines datasets from electron-positron and proton-proton collisions for a more precise gamma measurement.

Findings

Measured gamma as (71.3 ± 5.0) degrees.

Achieved the most precise single gamma measurement.

Applied a novel, model-independent analysis method.

Abstract

A measurement of the CKM angle $\gamma$ and related strong-phase parameters is performed using a novel, model-independent approach in ${B^{\pm}\rightarrow D(\rightarrow K^{0}_{\rm S} h^{\prime+}h^{\prime-}) h^{\pm}}$ decays, where $h^{(\prime)} \equiv \pi, K$. The analysis uses a joint data sample of electron-positron collisions collected by the BESIII experiment at the Beijing Electron-Positron Collider II during 2010--2011 and 2021--2022, corresponding to an integrated luminosity of 8 fb$^{-1}$, and proton-proton collisions collected by the LHCb experiment at the Large Hadron Collider during 2011--2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The two datasets are analyzed simultaneously by applying per-event weights based on the amplitude variation over the $D$-decay phase space to enhance the sensitivity to $C\!P$-violating observables. The CKM angle $\gamma$ is determined to be $\gamma = (71.3\pm 5.0)^{\circ}$, which constitutes the most precise single measurement to date.