A search for direct CP violation in D0 > h h+ (where h=K or pi) is presented using data corresponding to an integrated luminosity of 1.0 fb^1 collected in 2011 by LHCb in pp collisions at a centreofmass energy of 7 TeV. The analysis uses D0 mesons produced in inclusive semileptonic bhadron decays to the D0 mu X final state, where the charge of the accompanying muon is used to tag the flavour of the D0 meson. The difference in the CPviolating asymmetries between the two decay channels is measured to be Delta A_CP = A_CP(KK+)  A_CP(pipi+) = (0.49 + 0.30 (stat) + 0.14 (syst)) % . This result does not confirm the evidence for direct CP violation in the charm sector reported in other analyses.
Invariant mass distributions for (a, c) $ D ^0 \rightarrow K ^ K ^+ $ and (b, d) $ D ^0 \rightarrow \pi ^ \pi ^+ $ muontagged candidates for the two magnet polarities. The result of the fit is overlaid, showing the contribution from signal, combinatorial background and $ D ^0 \rightarrow K ^ \pi ^+ $ reflection. Underneath each plot the pull in each mass bin is shown. 
plot_a[..].pdf [36 KiB] HiDef png [215 KiB] Thumbnail [181 KiB] *.C file 

plot_a[..].pdf [36 KiB] HiDef png [231 KiB] Thumbnail [201 KiB] *.C file 

plot_a[..].pdf [35 KiB] HiDef png [207 KiB] Thumbnail [173 KiB] *.C file 

plot_a[..].pdf [36 KiB] HiDef png [227 KiB] Thumbnail [194 KiB] *.C file 

Kinematic distributions of the (a, c) $ D ^0$ meson and (b, d) muon for $ D ^0 \rightarrow \pi ^ \pi ^+ $ (black circles) and $ D ^0 \rightarrow K ^ K ^+ $ (red squares) candidates normalised to unit area. The histograms show the distributions of signal candidates, after background subtraction. Underneath each plot the ratio of the two distributions is shown. 
plot_u[..].pdf [22 KiB] HiDef png [186 KiB] Thumbnail [179 KiB] *.C file 

plot_u[..].pdf [21 KiB] HiDef png [193 KiB] Thumbnail [185 KiB] *.C file 

plot_u[..].pdf [20 KiB] HiDef png [167 KiB] Thumbnail [163 KiB] *.C file 

plot_u[..].pdf [21 KiB] HiDef png [166 KiB] Thumbnail [161 KiB] *.C file 

Kinematic distributions of the (a, c) $ D ^0$ meson and (b, d) muon for $ D ^0 \rightarrow \pi ^ \pi ^+ $ (black circles) and $ D ^0 \rightarrow K ^ K ^+ $ (red squares) candidates normalised to unit area after the weighting procedure. The histograms show the distributions of signal candidates, after background subtraction. Underneath each plot the ratio of the two distributions is shown. 
plot_u[..].pdf [22 KiB] HiDef png [183 KiB] Thumbnail [171 KiB] *.C file 

plot_u[..].pdf [21 KiB] HiDef png [193 KiB] Thumbnail [184 KiB] *.C file 

plot_u[..].pdf [21 KiB] HiDef png [172 KiB] Thumbnail [163 KiB] *.C file 

plot_u[..].pdf [21 KiB] HiDef png [163 KiB] Thumbnail [154 KiB] *.C file 

Decay time distribution for signal candidates (solid points) with the result from the fit overlaid for (a) $ D ^0 \rightarrow K ^ K ^+ $ and (b) $ D ^0 \rightarrow \pi ^ \pi ^+ $ decays. The distribution for background candidates scaled to a $\pm34 {\mathrm{ Me V /}c^2} $ window around the nominal $ D ^0$ mass is shown in the shaded (green) region. The distributions for signal and background candidates are obtained using the sPlot method. 
lifeti[..].pdf [10 KiB] HiDef png [181 KiB] Thumbnail [159 KiB] *.C file 

lifeti[..].pdf [10 KiB] HiDef png [178 KiB] Thumbnail [153 KiB] *.C file 

Raw asymmetries and $\Delta A_{ C P }$ as a function of (a) $p_{\rm T}$ and (b) $\eta$ of the $ D ^0$ meson. No weighting is applied. 
plot_c[..].pdf [15 KiB] HiDef png [122 KiB] Thumbnail [118 KiB] *.C file 

plot_c[..].pdf [14 KiB] HiDef png [102 KiB] Thumbnail [102 KiB] *.C file 

Animated gif made out of all figures. 
PAPER2013003.gif Thumbnail 
Unweighted raw asymmetries (in %) for the $ D ^0 \rightarrow \pi ^ \pi ^+ $ , $ D ^0 \rightarrow K ^ K ^+ $ and $ D ^0 \rightarrow K ^ \pi ^+ $ decays for the two magnet polarities. The mean value is the arithmetic average over the two polarities. The uncertainties are statistical only. 
Table_1.pdf [53 KiB] HiDef png [69 KiB] Thumbnail [35 KiB] tex code 

Weighted raw asymmetries (in %) for the $ D ^0 \rightarrow \pi ^ \pi ^+ $ and $ D ^0 \rightarrow K ^ K ^+ $ decays for the two magnet polarities. The mean value is the arithmetic average over the two polarities. The uncertainties are statistical only. 
Table_2.pdf [52 KiB] HiDef png [53 KiB] Thumbnail [27 KiB] tex code 

Contributions to the systematic uncertainty of $\Delta A_{ C P }$ . 
Table_3.pdf [81 KiB] HiDef png [160 KiB] Thumbnail [79 KiB] tex code 
Created on 17 August 2019.Citation count from INSPIRE on 23 August 2019.