New FOCUS results on charm mixing and CP violation

We present a summary of recent results on CP violation and mixing in the ch arm quark sector based on a high-statistics sample collected by photoproduc tion experiment FOCUS (E831 at Fermilab). We have measured the difference i n lifetimes for the D-0 decays: D-0 --> K(-)pi (+) and D-0 --> K-K+. This t ranslates into a measurement of the y(CP) mixing parameter in the D-0(D) ov er bar (0) system, under the assumptions that K-K+ is an equal mixture of C P odd and CP even eigenstates, and CP violation is negligible in the neutra l charm meson system. We verified the latter assumption by searching for CP violating asymmetry in the Cabibbo suppressed decay modes D+-->K(-)K(+)pi (+)(1) D-0-->K-K+ and D-0 --> pi (-)pi (+). We report preliminary results o n a measurement of tile branching ratio Gamma (D*(+)--> pi (+)(K(+)pi (-))) /Gamma (D*(+) --> pi (+)(K(-)pi (+))).