Hyperfine Mixing and the Semileptonic Decays of Double-Heavy Baryons in a Quark Model

Abstract

The semileptonic decays of the lowest-lying double-heavy baryons is treated in a quark model. For the ${\Xi }_{bb}$, hyperfine mixing in the spin wave function leaves the total rate for decay into the lowest lying daughter baryons essentially unchanged, but changes the relative rates into the ${\Xi }_{bc}$ and ${\Xi }_{bc}^{\prime }$. The same pattern is obtained in the decays of the ${\Omega }_{bb}$. For the ${\Xi }_{bc}$, this mixing leads to factor of about 17 suppression in the decay rate to the ${\Xi }_{cc}^{\ast }$, and a factor of two suppression in the total decay rate. For the ${\Omega }_{bc}$, the decay to the ${\Omega }_{cc}^{\ast }$ is suppressed by a factor of more than 30 from the unmixed case, and the total decay rate is decreased to about 40% of the decay rate obtained when mixing is ignored.

Comments: 7 pages