CDF results on CP violation in charm

TL;DR

This paper reports measurements of CP-violating asymmetries in charm meson decays using data from the Fermilab experiment, finding results consistent with Standard Model predictions and previous experiments.

Contribution

First measurement of $A_ au$ asymmetries in charm decays using a large Fermilab dataset with improved analysis techniques.

Findings

Measured $A_ au(K^+K^-)$ and $A_ au(\pi^+\pi^-)$ with uncertainties.

Combined asymmetry $A_ au$ consistent with Standard Model.

Results agree with previous experimental determinations.

Abstract

I discuss the measurement of CP-violating asymmetries ($A_{\Gamma}$) between effective lifetimes of $D^0$ or $\bar{D}^0$ mesons. Fully reconstructed $D^0\to K^+ K^-$ and $D^0\to \pi^+\pi^-$ decays collected in $p\bar{p}$ collisions by the Collider Detector at Fermilab experiment and corresponding to a data set of $9.7$~fb$^{-1}$ of integrated luminosity are used. The flavor of the charm meson at production is determined by exploiting the decay $D^{*+} \to D^0 \pi^+$. Contamination from mesons originated in $b$-hadron decays is subtracted from the sample. Signal yields as functions of the observed decay-time distributions are determined using likelihood fits and used to measure the asymmetries. The results, $A_\Gamma (K^+K^-) = \bigl(-1.9 \pm 1.5~(stat) \pm 0.4~(syst) \bigr)\times10^{-3}$ and $A_\Gamma (\pi^+\pi^-)= \bigl(-0.1 \pm 1.8~(stat) \pm 0.3~(syst) \bigr)\times10^{-3}$, and their combination, $A_\Gamma = \bigl(-1.2 \pm 1.2 \bigr)\times10^{-3}$, are consistent with the SM predictions and other experimental determinations.