Ao. Barvinsky et V. Krykhtin, DIRAC AND BFV QUANTIZATION METHODS IN THE 1-LOOP APPROXIMATION - CLOSURE OF THE QUANTUM CONSTRAINT ALGEBRA AND THE CONSERVED INNER-PRODUCT, Classical and quantum gravity, 10(10), 1993, pp. 1957-1984
Operator realization of quantum constraints and the lowest-order struc
ture functions is found in the 1-loop (linear in HBAR) approximation o
f the Dirac and BFV quantization for the general gauge theory subject
to first-class constraints. Semiclassical equivalence of the Dirac and
BFV methods to the reduced quantization of physical variables is esta
blished in terms of the conserved inner product in the space of physic
al states. The global obstructions to this result are briefly discusse
d in connection with the ideas of the secondary (third) quantization o
f constrained systems.