CP asymmetries in singly-Cabibbo-suppressed D decays to two pseudoscalar mesons

The LHCb Collaboration has recently reported evidence for a CP asymmetry approaching the percent level in the difference between D-0 -> pi(+) pi(-) and D-0 -> K+ K-. We analyze this effect as if it is due to a penguin amplitude with the weak phase of the standard model c -> b -> u loop diagram, but with a CP-conserving enhancement as if due to the strong interactions. In such a case the magnitude and strong phase of this amplitude P-b are correlated in order to fit the observed CP asymmetry, and one may predict CP asymmetries for a number of other singly-Cabibbo-suppressed decays of charmed mesons to a pair of pseudoscalar mesons. Nonzero CP asymmetries are expected for D+ -> K+(K) over bar (0)( the most promising channel for which a nonzero CP asymmetry has not yet been reported), as well as D-0 -> pi(0) pi(0), D-s(+) -> pi(+) K-0 and D-s -> pi(0) K+. No CP asymmetry is predicted for D+ -> pi(+) pi(0) or D-0 -> K-0(K) over bar (0) in this framework.