Baryons with two heavy quarks: Masses, production, decays, and detection

The large number of $B_c$ mesons observed by LHCb suggests a sizable cross section for producing doubly-heavy baryons in the same experiment. Motivated by this, we estimate masses of the doubly-heavy $J=1\mathrm{/}2$ baryons ${\mathrm{\Xi }}_{cc}$, ${\mathrm{\Xi }}_{bb}$, and ${\mathrm{\Xi }}_{bc}$, and their $J=3\mathrm{/}2$ hyperfine partners, using a method which accurately predicts the masses of ground-state baryons with a single heavy quark. We obtain $M({\mathrm{\Xi }}_{cc})=3627\pm 12$ MeV, $M(\Xi_{cc}^)= 3690 \pm 12$MeV,$M(\Xi_{bb}) = 10162 \pm 12$MeV,$M(\Xi_{bb}^)= 10184 \pm 12$MeV,$M(\Xi_{bc}) = 6914 \pm 13$MeV,$M(\Xi’{bc}) = 6933 \pm 12$MeV,and$M(\Xi{bc}^*) = 6969 \pm 14$ MeV. As a byproduct, we estimate the hyperfine splitting between $B_c^{\ast }$ and $B_c$ mesons to be $68\pm 8$ MeV. We discuss P-wave excitations, production mechanisms, decay modes, lifetimes, and prospects for detection of the doubly heavy baryons.