Revisiting nonfactorizable contributions to factorization-forbidden decays of $B$ mesons to charmonium

TL;DR

This paper investigates nonfactorizable gluon exchange contributions to certain B meson decays into charmonium states, explaining large observed decay rates and predicting measurable branching ratios and CP asymmetries.

Contribution

It provides a detailed analysis of nonfactorizable effects in factorization-forbidden B decays, showing they can account for large experimental decay rates and offering predictions for unmeasured decay channels.

Findings

Spectator contributions can produce large branching ratios consistent with experiments.

Predicted branching ratios are around 10^{-6}, accessible to Belle-II and LHCb.

Calculated CP asymmetries provide testable predictions for future experiments.

Abstract

Motivated by the large rates of $B\rightarrow (\chi_{c0}, \chi_{c2}, h_c)K$ decays observed by the $BABAR$ and Belle collaborations, we investigate the nonfactorizable contributions to these factorization-forbidden decays, which can occur through a gluon exchange between the $c\bar c$ system and the spectator quark. Our numerical results demonstrate that the spectator contributions are capable of producing a large branching ratio consistent with the experiments. As a by-product, we also study the Cabibbo-suppressed decays, such as $B\rightarrow (\chi_{c0}, \chi_{c2}, h_c)\pi$ and the U-spin-related $B_s$ decay, which have so far received less theoretical and experimental attention. The calculated branching ratios reach the order of $10^{-6}$, which in within the scope of the Belle-II and LHCb experiments. Further, the $CP$-asymmetry parameters are also calculated for these decays. The obtained results are compared with the available experimental data and numbers from other predictions. We also investigate the sources of theoretical uncertainties in our calculation.