New Focus Results on Charm Mixing and CP Violation

We present a summary of recent results on CP violation and mixing in the charm quark sector based on a high statistics sample collected by photoproduction experiment FOCUS (E831 at Fermilab). We have measured the difference in lifetimes for the D0 decays: D0→K−π+ and D0→K−K+. This translates into a measurement of the yCP mixing parameter in the 0d0 system, under the assumptions that K−K+ is an equal mixture of CP odd and CP even eigenstates, and CP violation is negligible in the neutral charm meson system. We verified the latter assumption by searching for a CP violating asymmetry in the Cabibbo suppressed decay modes D+→K−K+π+, D0→K−K+ and D0→π−π+. We show preliminary results on a measurement of the branching ratio Γ (D∗+→π+ (K+π−) ) /Γ (D∗+→π+ (K−π+) ).