Measurement of $CP$ asymmetries in $D^{\pm}\rightarrow \eta^{\prime} \pi^{\pm}$ and $D_s^{\pm}\rightarrow \eta^{\prime} \pi^{\pm}$ decays

A search for CP violation in D±→η′π± and Ds±→η′π± decays is performed using proton–proton collision data, corresponding to an integrated luminosity of 3 fb−1 , recorded by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV . The measured CP -violating charge asymmetries are ACP(D±→η′π±)=(−0.61±0.72±0.53±0.12)% and ACP(Ds±→η′π±)=(−0.82±0.36±0.22±0.27)% , where the first uncertainties are statistical, the second systematic, and the third are the uncertainties on the ACP(D±→KS0π±) and ACP(Ds±→ϕπ±) measurements used for calibration. The results represent the most precise measurements of these asymmetries to date.