Two Topics in Particle-Antiparticle Mixing

This paper summarizes two experimental issues in the study of particle antiparticle mixing. We propose a new method to extract the ratio $|V_{ts}/V_{td}|^2$ from a measurement of $\Delta \Gamma/\Gamma$ for the $B_s$ meson. This method is experimentally more sensitive than the conventional method for large values of $|V_{ts}|$ but depends on the accuracy of parton level calculations. We then briefly discuss the implications of large CP violation and final state interactions (FSI) in the experimental search for $D^0-\bar{D}^0$ mixing. The work described here was carried out in collaboration with S. Pakvasa.