Testing the W-exchange mechanism with two-body baryonic B decays

• Published in: arXiv.org
• Main Authors: Hsiao, Y K, Tsai, Shang-Yuu, Chong-Chung, Lih, Rodrigues, Eduardo
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 06.04.2020
• Subjects: Baryons; Charm (particle physics); Decay; Exchanging; Physics - High Energy Physics - Experiment; Physics - High Energy Physics - Phenomenology; Topology
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1906.01805

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 \(B\to {\bf B}_c \bar {\bf B}'\) decays provide a good test-bed for the study of the \(W\)-exchange topology, whose contribution is found to be non-negligible; here \({\bf B}_c\) is an anti-triplet or a sextet charmed baryon, and \({\bf \bar B}'\) an octet charmless (anti-)baryon. In particular, we calculate that \({\cal B}(\bar B^0\to\Sigma_c^{+}\bar p)=(2.9^{+0.8}_{-0.9})\times 10^{-6}\) in good agreement with the experimental upper bound. Its cousin \(\bar B_s^0\) mode, \(\bar B_s^0\to\Lambda^+_c\bar p\), is a purely \(W\)-exchange decay, hence is naturally suited for the study of the role of the \(W\)-exchange topology. We predict \({\cal B}(\bar B_s^0\to\Lambda^+_c\bar p)=(0.8\pm 0.3)\times 10^{-6}\), a relatively large branching ratio to be tested with a future measurement by the LHCb collaboration. Other predictions, such as \({\cal B}(\bar B^0\to\Xi_c^+\bar\Sigma^-)=(1.1\pm 0.4)\times 10^{-5}\), can be tested with future Belle II measurements.