New Universality of Baryon Isgur--Wise Form Factor in the Large $N_c$ limit

Abstract

New universality appears for the baryon Isgur--Wise form factor in the large $N_c$ limit. It is found that the semileptonic $Λ_b \rightarrow Λ_c$ and $Σ_b^{(*)} \rightarrow Σ^{(*)}_c$ decays are described by the same form factor, which can be calculated analytically. In the exact chiral $SU(3)$ limit, the same form factor is applicable to semileptonic $Ω_b^{(*)} \rightarrow Ω^{(*)}_c$ decays.