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

TL;DR

This paper searches for $CP$ violation in $D^0 o K^+K^- o ext{pi}^+ ext{pi}^-$ decays using $T$-odd correlations, finding no significant evidence of violation within the measured precision.

Contribution

It presents the first measurement of $CP$ violation using $T$-odd correlations in this decay mode with data from LHCb, setting limits on $CP$ asymmetry.

Findings

Measured $a_{CP}^{T ext{-odd}}$ as (0.18 ± 0.29 (stat) ± 0.04 (syst))%

No significant $CP$ violation observed in any phase space region

Results are consistent with the $CP$ conservation hypothesis

Abstract

A search for $CP$ violation using $T$-odd correlations is performed using the four-body $D^0 \to K^+K^-\pi^+\pi^-$ decay, selected from semileptonic $B$ decays. The data sample corresponds to integrated luminosities of $1.0\,\text{fb}^{-1}$ and $2.0\,\text{fb}^{-1}$ recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The $CP$-violating asymmetry $a_{CP}^{T\text{-odd}}$ is measured to be $(0.18\pm 0.29\text{(stat)}\pm 0.04\text{(syst)})\%$. Searches for $CP$ violation in different regions of phase space of the four-body decay, and as a function of the $D^0$ decay time, are also presented. No significant deviation from the $CP$ conservation hypothesis is found.