Anomalies in Hadronic $B$ Decays

Abstract

The decays $B\to PP$, where the pseudoscalar $P$ is a $π$ or $K$, have been studied under the assumption of flavour SU(3) symmetry [SU(3)$_F$]. The global fit shows a 3.6$σ$ discrepancy with the Standard Model (SM). Separate fits for $ΔS = 0$ and $ΔS = 1$ decays find parameter sets that differ by a factor of 10, suggesting 1000% SU(3)$_F$ breaking, significantly larger than the $\sim$ 30% breaking expected in the SM. This study has been extended to include final states with $η$ and $η'$ mesons. The resulting global fit, once again under the assumption of SU(3)$_F$ symmetry, is worse, with a 4.1$σ$ deviation from the SM. When theoretical constraints $|\widetilde C/\widetilde T| = 0.2$ or $\widetilde A = 0$ are imposed, the fits worsen, with the discrepancy approaching 5$σ$. These results hint at new-physics contributions to these decays.