Excited ${\Lambda }_Q$ Baryons in the Large $N_c$ Limit

Abstract

The spectrum of excited ${\Lambda }_Q$-type heavy baryons is considered in the large $N_c$ limit. The universal form factors for ${\Lambda }_b$ semileptonic decay to excited charmed baryons are calculated in the large $N_c$ limit. We find that the Bjorken sum rule (for the slope of the Isgur--Wise function) and Voloshin sum rule (for the mass of the light degrees of freedom) are saturated by the first doublet of excited ${\Lambda }_Q$ states.

Comments: 9 pages, use phyzzx, CALT-68-1919