B0−B¯0mixing and the weak-interaction phase

Abstract

The amount of $B^0-{\overline{B}}^0$ mixing as seen in the rate of same-sign leptons in $e^{+}{e}^{-}\to B^0{\overline{B}}^0\to \mathrm{llX}$ is a sensitive way to measure the phase ($\mathrm{sign}\mathrm{of}cos\delta$) in the Kobayashi-Maskawa matrix. It is shown how a rough measurement of the same-sign dilepton rate can determine the quadrant $\delta$ is in.