B--> eta' X_s in the Standard Model

We study $B \to \eta' X_s$ within the framework of the Standard Model. Several mechanisms such as $b \to \eta' s g$ through the QCD anomaly, and $b \to \eta's$ and $B\to \eta' s \bar q$ arising from four-quark operators are treated simultaneously. Using QCD equations of motion, we relate the effective Hamiltonian for the first mechanism to that for the latter two. By incorporating next-to-leading-logarithmic(NLL) contributions, the first mechanism is shown to give a significant branching ratio for $B\to \eta' X_s$, while the other two mechanisms account for about 15% of the experimental value. The Standard Model prediction for $B\to \eta' X_s$ is consistent with the CLEO data.