Measurement of the $C\!P$-even fraction of $D^0\to K^+K^-\pi^+\pi^-$

TL;DR

This paper measures the $C ext{P}$-even fraction of the decay $D^0 o K^+K^-\pi^+\pi^-$ using data from BESIII, providing the first model-independent determination of this quantity with high precision.

Contribution

It presents the first model-independent measurement of the $C ext{P}$-even fraction in $D^0 o K^+K^-\pi^+\pi^-$ decays using double-tagged events from BESIII data.

Findings

$F_+ = 0.730 \, ext{with uncertainties}$

First model-independent measurement of this decay's $C ext{P}$-even fraction

High-precision result with statistical and systematic uncertainties

Abstract

A determination of the $C\!P$-even fraction $F_+$ in the decay $D^0 \to K^+K^-\pi^+\pi^-$ is presented. Using $2.93$ fb$^{-1}$ of $e^+e^-\to\psi(3770)\to D\bar{D}$ data collected by the BESIII detector, one charm meson is reconstructed in the signal mode and the other in a $C\!P$ eigenstate or the decay $D\to K_{S, L}^0\pi^+\pi^-$. Analysis of the relative rates of these double-tagged events yields the result $F_+ = 0.730 \pm 0.037 \pm 0.021$, where the first uncertainty is statistical and the second is systematic. This is the first model-independent measurement of $F_+$ in $D^0 \to K^+K^-\pi^+\pi^-$ decays.