UC Irvine

We extend the range of predictions of the isosinglet (or vector) down quark model to the fully allowed physical ranges, and also update this with the effect of new physics constraints. We constrain the present allowed ranges of sin(2β) and sin(2α), γ, xs, and ABs. In models allowing mixing to a new isosinglet down quark (as in E6) flavor changing neutral currents are induced that allow a Z0 mediated contribution to B - B̄ mixing and which bring in new phases. In (ρ, η), (xs ,sin(γ)), and (xs ,ABxs) plots for the extra isosinglet down quark model which are herein extended to the full physical range, we find new allowed regions that will require experiments on sin(γ) and/or xs to verify or to rule out an extra down quark contribution.