Heavy Quark Limit of Weak Transition Form Factors in a Light-Cone Constituent Quark Model

In the light-cone constituent quark model, the wavefunction for Λ_b⁰ or Λ_c⁺ with three quarks is reduced to a wavefunction for the heavy-quark-diquark picture by assuming that the two light quarks forming a diquark are in comoving. A heavy quark (or diquark) distribution amplitude is obtained. While form factors of weak transition Λ_b → Λ,ev are calculated in the finite mass case, a hadronic-size-dependen t form of Isgur- Wise function is obtained in the m_Q → ∞ limit.