New Exact Heavy Quark Sum Rules
  Considering nonforward scattering amplitude off the heavy quark in the Small Velocity limit two exact superconvergent sum rules are derived. The first sum rule leads to the lower bound \rho^2 > 3/4 for the slope of the Isgur-Wise function. It also provides the rationale for the fact that the vector heavy flavor mesons are heavier than the pseudoscalar ones. A spin-nonsinglet analogue \bar\Sigma of \bar\Lambda = M_B-m_b is introduced. 
Nikolai Uraltsev