Weak Decays of Doubly Heavy Baryons: SU(3) Analysis

Motivated by the recent LHCb observation of doubly-charmed baryon ${\mathrm{\Xi }}_{cc}^{++}$ in the ${\mathrm{\Lambda }}_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+}$ final state, we analyze the weak decays of doubly heavy baryons ${\mathrm{\Xi }}_{cc}$, ${\mathrm{\Omega }}_{cc}$, ${\mathrm{\Xi }}_{bc}$, ${\mathrm{\Omega }}_{bc}$, ${\mathrm{\Xi }}_{bb}$ and ${\mathrm{\Omega }}_{bb}$ under the flavor SU(3) symmetry. Decay amplitudes for various semileptonic and nonleptonic decays are parametrized in terms of a few SU(3) irreducible amplitudes. We find a number of relations or sum rules between decay widths and CP asymmetries, which can be examined in future measurements at experimental facilities like LHC, Belle II and CEPC. Moreover once a few decay branching fractions are measured in future, some of these relations may provide hints for exploration of new decay modes.