First measurement of F_+^{4\pi} in D ->4\pi decays and a new method for measuring CPV in charm decays

TL;DR

This paper reports the first measurement of the CP-even content in D->4pi decays, demonstrating its potential for improved CP violation and CKM angle measurements in charm physics using a novel time-dependent inclusive analysis method.

Contribution

It introduces a new measurement of the CP-even fraction in D->4pi decays and proposes a novel method for measuring CP violation in charm decays using quantum correlated D decays.

Findings

Measured plus = 0.737 ± 0.028 for D->4pi decays.

The high plus value makes the decay mode suitable for CP violation studies.

The new method improves sensitivity for measuring CP violation and mixing parameters.

Abstract

A first measurement of \fplus, the \CP-even content of the decay D->4pi using decays of $\psi(3770)$ to quantum correlated $D\bar{D}$ decays collected by the CLEO-c experiment is presented. The measured value is \fplus=$0.737 \pm 0.028$. This relatively high value makes the decay mode particularly suitable for both measurements of the CKM angle $\gamma$ and charm \CP-violation in a model independent way. This novel approach to studying indirect \CP-violation in charm decays is based on the time-dependent inclusive analysis of multi body self-conjugate states. These final states can be used to determine the indirect CP-violating observable $A_{\Gamma}$ and the mixing observable $y_{CP}$ provided that $F_+$ is known. This approach can yield significantly improved sensitivity compared with the conventional method that relies on decays to \CP~eigenstates.