One interesting new sum rule extending Bjorken's to order 1/m(Q)

We explicitly check quark-hadron duality to order (m(b) - m(c))Lambda/m(b)( 2), for b --> clv decays in the limit m(b) - m(c) much less than m(b) inclu ding ground state and orbitally excited hadrons. Duality occurs thanks to a new sum rule which expresses the subleading HQET form factor xi(3) or, in other notations, a(+)((1)) in terms of the infinite mass limit form factors and some level splittings. We also demonstrate the sum rule, which is not restricted to the condition m(b) - m(c) much less than m(b), applying OPE t o the longitudinal axial component of the hadronic tensor without neglectin g the 1/m(b) subleading contributions to the form factors. We argue that th is method should produce a new class of sum rules, depending on the current , beyond Bjorken, Voloshin and the known tower of higher moments. Applying OPE to the vector currents we find another derivation of the Voloshin sum r ule. From independent results on xi(3) we derive a sum rule which involves only the tau(1/2)((n)) and tau(3/2)((n)) form factors and the corresponding level splittings. The latter strongly supports a theoretical evidence that the B semileptonic decay into narrow orbitally-excited resonances dominate s over the decay into the broad ones, in apparent contradiction with some r ecent experiments. We discuss this issue. (C) 2000 Elsevier Science B.V. Al l rights reserved.