Updated bounds on CP asymmetries in $B^0\to {\eta }^{\prime }{K}_S$ and $B^0\to {\pi }^0{K}_S$

Abstract

New rate measurements of $B^0$ decays into ${\pi }^0{\pi }^0,{\pi }^0\eta ,{\pi }^0{\eta }^{\prime },\eta \eta ,\eta {\eta }^{\prime },{\eta }^{\prime }{\eta }^{\prime }$ and $K^{+}{K}^{-}$ are used in conjunction with flavor SU(3) to constrain the coefficients $S$ and $C$ of $\sin \Delta mt$ and $\cos \Delta mt$ in the time-dependent CP asymmetries of $B^0\to {\eta }^{\prime }{K}_S$ and $B^0\to {\pi }^0{K}_S$. Experimental values of $S_{{\eta }^{\prime }K}$ are now seen to be closer to the Standard Model expectations, fully consistent with the new improved bounds.

10 pages, 3 figures. To be published in Phys. Rev. D. Discussion and references expanded; data updated