${\eta }^{\mathrm{\prime }}$ production in B-decays: Standard Model vs. New Physics

Standard model factorization can account for the large rate for $B^\pm \to \eta’ K^\pm$\mathrm{.}Thelargeratefor$B \to \eta’ X_s$ is more problematic and requires a cocktail'' solution. Individual contributions from factorization, $b \to \eta' s g$, and intrinsic charm’’ fall significantly short of the observed rate. In contrast, the observed ${\eta }^{\mathrm{\prime }}$ yields are easily explained in models with $B(b\to sg)\sim 15$. Factorization can account for the entire semi-inclusive ${\eta }^{\mathrm{\prime }}$ yield without violating rare decay constraints. Implications for CP violation are discussed.