The baryon Isgur-Wise function in the large-Nc limit

In the large-Nc limit, the Λb and Λc can be treated as bound states of chiral solitons and mesons containing a heavy quark. We show that the soliton and heavy meson are bound in an attractive harmonic oscillator potential. The Isgur-Wise function for Λb → Λce−νe decay is computed in the large-Nc limit. Corrections to the form factor which depend on mN/mQ can be summed exactly (mN and mQ are the nucleon and heavy quark masses). We find that this symmetry breaking correction at zero recoil is only 1%.