Abstract

We study the decays in the perturbative QCD (PQCD) approach, involving the puzzling resonance , where P represents a light pseudoscalar meson (K or π). Assuming to be a charmonium state, we obtain the following results. (a) The branching ratios of the and decays are consistent with the results predicted by the covariant light-front approach within errors; however, they are larger than those given by the generalized factorization approach. (b) The branching ratio of the decay is predicted as , which is smaller than the previous PQCD calculation result but still slightly larger than the upper limits set by Belle and BaBar. Hence, we suggest that the decays should be precisely measured by the LHCb and Belle II experiments to help probe the inner structure of . (c) Compared with the decays, the decays have significantly smaller branching ratios, which drop to values as low as . (d) The direct CP violations of these considered decays are small () because the penguin contributions are loop suppressed compared to the tree contributions. The mixing-induced CP violation of the decay is highly consistent with the current world average value %. Experimentally testing the results for the branching ratios and CP violations, including the implicit and isospin symmetries of these decays, helps probe the nature of .

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