Measurement of the $D\to K^-\pi^+$ strong phase difference in $\psi(3770)\to D^0\overline{D}{}^0$

We study D-0(D) over bar (0) pairs produced in e(+)e(-) collisions at root s = 3.773 GeV using a data sample of 2.92 fb(-1) collected with the BESIII detector. We measured the asymmetry A(K pi)(CP) of the branching fractions of D -> K-pi(+) in CP-odd and CP-even eigenstates to be (12.7 +/- 1.3 +/- 0.7) x 10(-2). A(K pi)(CP) can be used to extract the strong phase difference delta(K pi) between the doubly Cabibbo-suppressed process (D) over bar (0) -> K-pi(+) and the Cabibbo-favored process D-0 -> K-pi(+). Using world-average values of external parameters, we obtain cos delta(K pi) = 1.02 +/- 0.11 +/- 0.06 +/- 0.01. Here, the first and second uncertainties are statistical and systematic, respectively, while the third uncertainty arises from the external parameters. This is the most precise measurement of delta(K pi) to date. (C) 2014 The Authors. Published by Elsevier B.V.