Duality in the non-relativistic harmonic oscillator quark model in the Shifman-Voloshin limit: A pedagogical example

The detailed way in which duality between sum of exclusive states and the f ree quark model description operates in semileptonic total decay widths, is analysed. It is made very explicit by the use of the non relativistic harm onic oscillator quark model in the SV limit, and a simple interaction curre nt with the lepton pair. In particular, the Voloshin sum rule is found to e liminate the mismatches of order delta m/m(b)(2). (C) 2000 Elsevier Science B.V. All rights reserved.