Hyperfine effects and large [formula omitted] corrections

Abstract

Effects associated with hyperfine mass splitting between pseudoscalar and vector mesons may induce suprisingly large 1 m 2 Q corrections in the heavy quark expansion. We demonstrate this in a relativistic quark model by calculating to all orders in 1 m Q , with and without hyperfine effects, and comparing to the first order results. Total corrections of 30% or more are quite possible in the decay rates for B → Dlv and B → D ∗lv near zero recoil.