New Puzzles in Nonleptonic B and D Decays

Exclusive charged $B$ decays show an unexplained enhancement in low-lying channels which must be reversed in other channels to equalise charged and neutral lifetimes. One suggested explanation involves decay modes with excited mesons like the $a_1$. The anomalous behaviour of decay modes of D and B mesons into final states containing the $\eta$ and $\eta'$ mesons is discussed.