Why B meson decays produce charm baryons in pairs

B mesons can decay into pairs of charm baryons, a process LHCb recently observed for the first time. The authors model these decays using final-state rescattering—particles re-interacting after the initial decay—and find the predictions match the measured branching fractions. The theory predicts nearly zero CP violation but large polarization in one decay mode, a testable prediction for the next round of precision measurements.