Abstract
The role of W -exchange diagrams in baryonic B decays is poorly understood, and often taken as insignificant and neglected. We show that charmful two-body baryonic \( B\to {\mathbf{B}}_c\overline{\mathbf{B}}^{\prime } \) decays provide a good test-bed for the study of the W -exchange topology, whose contribution is found to be non-negligible; here Bc is an anti-triplet or a sextet charmed baryon, and \( \overline{\mathbf{B}}^{\prime } \) an octet charmless (anti-)baryon. In particular, we calculate that \( \mathrm{\mathcal{B}}\left({\overline{B}}^0\to {\Sigma}_c^{+}\overline{p}\right)=\left({2.9}_{-0.9}^{+0.8}\right)\times {10}^{-6} \) in good agreement with the experimental upper bound. Its cousin \( {\overline{B}}_s^0 \) mode, \( {\overline{B}}_s^0\to {\Lambda}_c^{+}\overline{p} \), is a purely W -exchange decay, hence is naturally suited for the study of the role of the W -exchange topology. We predict \( \mathrm{\mathcal{B}}\left({\overline{B}}_s^0\to {\Lambda}_c^{+}\overline{p}\right)=\left(0.8\pm 0.3\right)\times {10}^{-6} \), a relatively large branching ratio to be tested with a future measurement by the LHCb collaboration. Other predictions, such as \( \mathrm{\mathcal{B}}\left({\overline{B}}^0\to {\Xi}_c^{+}{\overline{\Sigma}}^{-}\right)=\left(1.1\pm 0.4\right)\times {10}^{-5} \), can be tested with future Belle II measurements.
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Hsiao, Y., Tsai, SY., Lih, CC. et al. Testing the W -exchange mechanism with two-body baryonic B decays. J. High Energ. Phys. 2020, 35 (2020). https://doi.org/10.1007/JHEP04(2020)035
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DOI: https://doi.org/10.1007/JHEP04(2020)035