Effects of a superheavy, weak-isoscalar quark on flavor-changing neutral current processes, especially charge-parity violation in Z0decay

A superheavy, weak-isoscalar, Q = -1/3 quark is added to the Standard Model, inducing tree-level flavor-changing neutral currents (TLFCNCs) involving only the Q = -1/3 quarks. Although constrained by current low-energy experimental data to be extremely weak, it is nonetheless found that the tree-level s ↔ d mixing strength could still be large enough to increase the absolute value of r/sub sd/ = [Gamma(Z0 → anti sd) - (s ↔ d)] Gamma/sub T/(Z0 → quarks) by a factor of 360 over its Standard Model-predicted upper limit. The K/sub L/0-K/sub s/0 mass difference Δm and K/sub L/0-K/sub s/0 mixing parameter anti epsilon are used as input to determine the behavior of the tree-level s ↔ d multiplicative mixing parameter