  The mixing parameter y_cp for the neutral D system can be obtained by
comparing the lifetimes of CP eigenstate decays of the D mesons. Recent results
on the lifetime differences from the Belle, CLEO, FOCUS(E831) experiments are
summarized in this article. The neutral D decay modes analyzed by the
experiments are: The D0->Kpi mode with the assumption that it is an equal
mixture of CP even and odd eigenstates, and the CP even modes D0->KK and
D0->pipi.
