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

Abstract

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 $J=1/2$ baryons $Ξ_{cc}$, $Ξ_{bb}$, and $Ξ_{bc}$, and their $J=3/2$ hyperfine partners, using a method which accurately predicts the masses of ground-state baryons with a single heavy quark. We obtain $M(Ξ_{cc}) = 3627 \pm 12$ MeV, $M(Ξ_{cc}^*)= 3690 \pm 12$ MeV, $M(Ξ_{bb}) = 10162 \pm 12$ MeV, $M(Ξ_{bb}^*)= 10184 \pm 12$ MeV, $M(Ξ_{bc}) = 6914 \pm 13$ MeV, $M(Ξ'_{bc}) = 6933 \pm 12$ MeV, and $M(Ξ_{bc}^*) = 6969 \pm 14$ MeV. As a byproduct, we estimate the hyperfine splitting between $B_c^*$ 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.

29 pages, no figures. More text and references added. To be published in Phys. Rev. D