B factory constraints on isosinglet down quark mixing, and predictions for other CP-violating experiments

In the main part of this paper are 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's that allow a Z(0) mediated contribution to B - (B) over bar mixing and which brings in new phases. We then repeat the chi(2) analysis, now including experimental constraints from FCNC's 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.