Anomalies in Hadronic $B$ Decays: an Update

TL;DR

This paper updates the analysis of hadronic B decays involving eta and eta' mesons, revealing significant discrepancies with the Standard Model predictions under SU(3) symmetry, even after considering large symmetry-breaking effects.

Contribution

It extends previous SU(3) symmetry analyses of B decays to include eta and eta' final states, demonstrating persistent anomalies with minimal theoretical assumptions.

Findings

Combined fit shows a 4.1σ discrepancy with SU(3) symmetry.

Large SU(3) breaking (~1000%) is needed to reconcile data.

Discrepancy increases to 4.9σ when QCD factorization input is included.

Abstract

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 $4.9\sigma$.