ExcitedΛQbaryons in the largeNclimit

The spectrum of excited ${\mathrm{\Lambda }}_{\mathit{Q}}$-type heavy baryons is considered in the large ${\mathit{N}}_{\mathit{c}}$ limit. The universal form factors for ${\mathrm{\Lambda }}_{\mathit{b}}$ semileptonic decay to excited charmed baryons are calculated in the large ${\mathit{N}}_{\mathit{c}}$ 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 ${\mathrm{\Lambda }}_{\mathit{Q}}$ states.