Search for $CP$ violation using $T$-odd correlations in $D^0\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$ decays

We search for $CP$ violation in a sample of $4.7\times {10}^4$ Cabibbo suppressed $D^0\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$ decays. We use $470{\mathrm{fb}}^{-1}$ of data recorded by the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage rings running at center-of-mass energies near 10.6 GeV. $CP$ violation is searched for in the difference between the $T$-odd asymmetries, obtained using triple product correlations, measured for $D^0$ and ${\overline{D}}^0$ decays. The measured $CP$ violation parameter is ${\mathcal{A}}_T=(1.0\pm {5.1}_{\mathrm{stat}}\pm {4.4}_{\mathrm{syst}})\times {10}^{-3}$.

Figure 1

(a) $m(K^{+}{K}^{-}{\pi }^{+}{\pi }^{-})$ vs $\Delta m$ for the total data sample. (b) $m(K^{+}{K}^{-}{\pi }^{+}{\pi }^{-})$ and (c) $\Delta m$ projections with curves from the fit results. Shaded areas indicate the different contributions. The fit residuals, represented by the pulls, are also shown under each distribution.

Figure 2

Fit projections onto the $m(K^{+}{K}^{-}{\pi }^{+}{\pi }^{-})$ for the four different $C_T$ subsamples with cut on $\Delta m$. The shaded areas indicate the total backgrounds. The fit residuals, represented by the pulls are also shown under each distribution.