Model-independent analysis of $\bbox{B}$-$\bbox{\bar B}$ mixing and $\bbox{CP}$ violation in $\bbox{B}$ decays

We present a framework to analyze effects of new physics beyond the standard model on $B$-$\bar B$ mixing and $CP$ violation in $B$ decays in a model-independent manner. Assuming that tree level decay amplitudes are dominated by the standard model ones, new physics contribution to the $B$-$\bar B$ mixing can be extracted from several measurements at $B$ factories. Using this framework, we show the present constraint on new physics contribution to the $B$-$\bar B$ mixing, and illustrate constraints expected to be given by future experiments at $B$ factories. We also point out a possibility that $CP$ asymmetries in $B\rightarrow\psi K_S$, $B\rightarrow\pi\pi$, and $B\rightarrow DK$ modes look consistent with the standard model, even if a large new physics contribution is present in the $B$-$\bar B$ mixing.