Branching Ratio and CP Asymmetry of $B^0\to {\eta }^{(\prime )}{\eta }^{(\prime )}$ Decays in the Perturbative QCD Approach

Abstract

We calculate the CP averaged branching ratios and CP-violating asymmetries for $B^0\to \eta \eta ,\eta {\eta }^{\prime }$ and ${\eta }^{\prime }{\eta }^{\prime }$ decays by employing the perturbative QCD (pQCD) factorization approach. The pQCD predictions for the CP-averaged branching ratios are $Br(B^0\to \eta \eta )\approx 0.67\times 10^{-7}$, $Br(B^0\to \eta {\eta }^{\prime })\approx 0.18\times 10^{-7}$, and $Br(B^0\to {\eta }^{\prime }{\eta }^{\prime })\approx 0.11\times 10^{-7}$, which are consistent with currently available experimental upper limits. We also predict large CP-violating asymmetries for the considered three decay modes, which can be tested by the future B meson experiments.

Comments: 27 pages, 6 ps/eps figures, more discussions about theoretical uncertainties, final version to appear in Phys. Rev. D