Anomalies in Hadronic $B$ Decays: an Update

Recently, $B\to PP$ decays ($B = \{B^0, B^+, B_s^0\}$, $P = \{ \pi, K \}$) were analyzed under the assumption of flavor SU(3) symmetry (SU(3)$_F$). Although the individual fits to $\Delta S=0$ or $\Delta S=1$ decays are good, it was found that the combined fit is very poor: there is a $3.6\sigma$ disagreement with the SU(3)$_F$ limit of the standard model (SM$_{\rm{SU(3)}_F}$). One can remove this discrepancy by adding SU(3)$_F$-breaking effects, but 1000\% SU(3)$_F$ breaking is required. In this paper, we extend this analysis to include decays in which there is an $\eta$ and/or $\eta'$ meson in the final state. We now find that the combined fit exhibits a $4.1\sigma$ discrepancy with the SM$_{\rm{SU(3)}_F}$, and 1000\% SU(3)$_F$-breaking effects are still required to explain the data. These results are rigorous, group-theoretically -- no theoretical assumptions have been made. But when one adds some theoretical input motivated by QCD factorization, the discrepancy with the SM$_{\rm{SU(3)}_F}$ grows to $4.9\sigma$.