Slope and curvature of Isgur-Wise function using variationally improved perturbation theory in a quantum chromodynamics inspired potential model

Abstract

We used variationally improved perturbation theory (VIPT) in calculating the slope and curvature of Isgur-Wise (I-W) function with the Cornell potential −\( \frac{{4\alpha _s }} {{3r}} \)+br + c instead of the usual stationary state perturbation theory as done earlier. We used −(4αs/3r), i.e. the Coulombic potential, as the parent and the linear one, i.e. br+c as the perturbed potential in the theory and calculated the slope and curvature of Isgur-Wise function including three states in the summation involved in the first-order correction to wave function in the method.