Search for CP violation in $D^0 \to h^+h^-$ decays at CDF

TL;DR

This paper reports a measurement of CP-violating asymmetries in $D^0$ meson decays using the full CDF dataset, finding results consistent with Standard Model predictions and previous experiments.

Contribution

First measurement of $A_ ext{Gamma}$ in $D^0$ decays at CDF with the full dataset, providing new constraints on CP violation in charm sector.

Findings

Measured $A_ ext{Gamma}(K^+K^-)$ and $A_ ext{Gamma}(\pi^+\pi^-)$ with uncertainties.

Results are consistent with Standard Model predictions.

Combined asymmetry $A_ ext{Gamma}$ is close to zero within errors.

Abstract

I report on a measurement of \CP-violating asymmetries ($A_{\Gamma}$) between effective lifetimes of $D^0$ or $\bar{D}^0$ in 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. The full CDF data set corresponding to $9.7$ fb$^{-1}$ of integrated luminosity is used. The flavor of the charm meson at production is determined by exploiting the strong-interaction decay $D^{*+} \to D^0 \pi^+$, while the contamination from mesons originated in $b$-hadron decays is evaluated and subtracted from the sample. Signal yields as functions of the observed decay-time distributions are extracted from maximum likelihood fits and used to measure the asymmetries. The results, $A_\Gamma (K^+K^-) = \bigl(-1.9 \pm 1.5 \mathrm{(stat)} \pm 0.4 \mathrm{(syst)} \bigr)\times10^{-3}$ and $A_\Gamma (\pi^+\pi^-)= \bigl(-0.1 \pm 1.8 \mathrm{(stat)} \pm 0.3 \mathrm{(syst)} \bigr)\times10^{-3}$, and their combination, $A_\Gamma = \bigl(-1.2 \pm 1.2\bigr)\times10^{-3}$, are consistent with the SM predictions and other experimental determinations.