B Factory Constraints on Isosinglet Down Quark Mixing, and Predictions For Other CP Violating Experiments

In the main part of the paper we project forward to having $B$ factory determinations of $\sin(2\beta)$ and $\sin(2\alpha)$, for which we take several values. First, we use a joint $\chi^2$ analysis of CKM experiments to constrain CKM matrix elements in the standard model, and experiments on the angles $\alpha$, $\beta$, and $\gamma$, and on $x_s$ and null $CP$ asymmetries. Then we invoke mixing to a new isosinglet down quark (as in E$_6$) which induces FCNC that allow a $Z^0$ mediated contribution to $B-\bar B$ mixing and which brings in new phases. We then repeat the $\chi^2$ analysis, now including experimental constraints from FCNC as well, finding much larger ranges of prediction for the $B$ factory. We then add projected $B$ factory results on $\sin(2\beta)$ and $\sin(2\alpha)$ and repeat both analyses. In $(\rho,\eta)$ and $(x_s,\sin{(\gamma)})$ plots for the extra isosinglet down quark model, we find multiple regions that will require experiments on $\sin{(\gamma)}$ and/or $x_s$ to decide between and possibly to effectively bound out the extra down quark contribution.