D^0-$\bar D^0$ Mixing and CP Violation from FOCUS Experiment

TL;DR

This paper reports on measurements of $D^0$-$ar D^0$ mixing and CP violation using a large charm particle dataset from the FOCUS experiment, finding evidence for mixing but no CP violation.

Contribution

First measurement of the mixing parameter $y_{cp}$ in charm mesons using high-statistics data from the FOCUS experiment, with no observed CP violation.

Findings

Measured $y_{cp}$ as (3.42 ± 1.39 ± 0.74)%

No evidence of CP violation in studied decay modes

Collected over 1 million charm particles in the experiment

Abstract

Measurement results on $D^0$-$\bar D^0$ mixing and CP violation are presented. FOCUS, a fixed target experiment at Fermilab, collected a high statistics photo-produced charm sample collected during the 96-97 run. We reconstructed more than 1 million charmed particles and compared the lifetimes of two $D^0$ meson decays to $K^-\pi^+$ and $K^-K^+$. The mixing parameter, $y_{\rm cp}$, we obtained is $(3.42\pm 1.39\pm 0.74)%$. We also searched CP asymmetries in $D^+\to K^-K^+\pi^+$, $D^0\to K^-K^+$ and $D^0\to \pi^-\pi^+$ decay modes. We did not see any evidence of CP violation by comparing the decay rates for particle and antiparticle.