Heavy quark limit in the model with confined light quarks and infrared   heavy quark propagators
  We have studied the weak decay constants and the Isgur-Wise form factor of the B and D mesons in the heavy quark limit, by employing a relativistic quark confinement model. It is an attempt to improve our previous work within the same line of thinking, but by incorporating a couple of novel aspects. First, the infrared behavior of the heavy quark is considered by modifying its conventional propagator in terms of a single parameter $\nu$. Second, the mass difference of the heavy meson and heavy quark: $E=m_H-M_Q$ has been included. It is found that the weak decay constants depend strongly on the mass difference E with a relatively mild $\nu$ dependence. As for the Isgur-Wise function it is controlled more sensitively by the infrared parameter $\nu$, leading to its suppression at maximum meson recoil. 
M. A. Ivanov (Laboratory of Theoretical Physics, Joint Institute for   Nuclear Research, Moscow, Russia) and T. Mizutani (De...