Quasi-two-body decays $B_c\to D^*h\to Dπh$ in the perturbative QCD

Abstract

In this work, we investigate the quasi-two-body decays $B_c\to D^*h\to Dπh$ with $h = (K^0,π^0,η,η^{\prime})$ using the perturbative QCD(PQCD) approach. The description of final state interactions between the $Dπ$ pair is achieved through the two-meson distribution amplitudes(DAs), which are normalized to the time-like form factor. The PQCD predictions on the branching ratios of the quasi-two-body decays $B_c\to D^*h\to Dπh$ show an obvious hierarchy: $Br(B_{c}^+ \to D^{*+} K^{0}\to D^0π^+K^{0})=({5.22}_{-0.74}^{+0.86})\times{10}^{-6}, Br(B_{c}^+ \to D^{*+} π^{0}\to D^0π^+π^{0})=(0.93\pm0.26)\times{10}^{-7}, Br(B_{c}^+ \to D^{*+} η\to D^0π^+η) =({2.83}_{-0.52}^{+0.59})\times{10}^{-8}$ and $Br(B_{c}^+ \to D^{*+} η^\prime\to D^0π^+η^\prime)=({1.89}_{-0.36}^{+0.40})\times{10}^{-8}$. From the invariant mass $m_{Dπ}$-dependence of the decay spectrum for each channel, one can find that the branching fraction is concentrated in a narrow region around the $D^{*}$ pole mass. So one can obtain the branching ratios for the corresponding two-body decays $B_c\to D^{*+}h$ under the narrow width approximation. We find that the branching ratios of the decays $B_c\to D^{*+}h$ are consistent well with the previous PQCD calculations within errors. These predictions will be tested by the future experiments.