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Abstract

A search for CP violation in $D^0 \rightarrow K^{-} K^{+} $ and $D^0
\rightarrow \pi^{-} \pi^{+} $ decays is performed using $pp$ collision data,
corresponding to an integrated luminosity of $3~fb^{-1}$, collected using the
LHCb detector at centre-of-mass energies of 7 and $8~$TeV. The flavour of the
charm meson is inferred from the charge of the pion in $D^{*+}\rightarrow
D^0\pi^+$ and $D^{*-}\rightarrow \bar{D^0}\pi^{-}$ decays. The difference
between the CP asymmetries in $D^0 \rightarrow K^{-} K^{+} $ and $D^0
\rightarrow \pi^{-} \pi^{+} $ decays, $\Delta A_{CP} \equiv A_{CP}(K^{-} K^{+})
- A_{CP}(\pi^{-} \pi^{+})$, is measured to be $\left( -0.10 \pm 0.08(stat) \pm
0.03(syst) \right) \%$. This is the most precise measurement of a
time-integrated CP asymmetry in the charm sector from a single experiment.