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 ${\Xi }_{cc}$, ${\Xi }_{bb}$, and ${\Xi }_{bc}$, 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 $M({\Xi }_{cc})=3627\pm 12$ MeV, $M({\Xi }_{cc}^{\ast })=3690\pm 12$ MeV, $M({\Xi }_{bb})=10162\pm 12$ MeV, $M({\Xi }_{bb}^{\ast })=10184\pm 12$ MeV, $M({\Xi }_{bc})=6914\pm 13$ MeV, $M({\Xi }_{bc}^{\prime })=6933\pm 12$ MeV, and $M({\Xi }_{bc}^{\ast })=6969\pm 14$ 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.

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