Measurement of the Direct CP-violating Charge Asymmetry in D±s→ϕπ± Decays

We present a measurement of the direct CP-violating charge asymmetry in D-s(+) -> phi pi(+/-) decays where the phi meson decays to K+ K-, using the full Run II data set with an integrated luminosity of 10.4 fb(-1) of proton- antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. The normalized difference A(CP) in the yield of D-s(+) and D-s(-) mesons in these decays is measured by fitting the difference between their reconstructed invariant mass distributions. This results in an asymmetry of A(CP) = [-0.38 +/- 0.27]%, which is the most precise measurement of this quantity to date. The result is consistent with the standard model prediction of zero CP asymmetry in this decay.