  Radial mixing in the pseudoscalar $\eta-\eta^{\prime}$ systems can be
generated from hyperfine interactions and annihilation terms. For the
$\eta-\eta^{\prime}$ system we find the effects of radial mixing are
appreciable and seriously affect the decay branching ratios for $B \to
\eta(\eta^{\prime})K(K^*)$, mainly by modifying the $B \to \eta(\eta^{\prime})$
form factors. In particular, the effect of radial mixing in conjunction with
the interference effects among penguin amplitudes can resolve puzzles in the $B
\to \eta(\eta^{\prime}) K$ decays. The decay $\Lambda_b \to \Lambda
\eta(\eta^{\prime})$ on the other hand is dominated by a single amplitude so
that the significant interference effects of B decays are absent here.
Moreover, since no $\Lambda_b \to \eta(\eta^{\prime})$ form factors are
involved here, the effect of radial mixing is essentially negligible. Hence,
unlike the B system, we do not predict a large enhancement of $\Lambda_b \to
\Lambda \eta^{\prime}$ relative to $\Lambda_b \to \Lambda \eta$.
