Star Product for Second Class Constraint Systems from a BRST Theory
I. A. Batalin, M. A. Grigoriev, S. L. Lyakhovich
TL;DR
This work tackles covariant deformation quantization of general second-class constraint systems on arbitrary symplectic manifolds by embedding the system into an extended phase space and converting the second-class constraints into an effective first-class, BRST-compatible set. The authors construct a Dirac-connected Fedosov-type geometry on the extended space and develop a BFV-BRST quantization that yields a star-product for the Dirac bracket, with a precise reduction to the constraint surface that recovers the Fedosov star-product. A key result is that, using a special Dirac connection, the original constraints become central in the star-commutator algebra, facilitating a clean reduction and a consistent quantum observables cohomology where $H^0$ corresponds to functions on the constraint surface $\Sigma$. The framework is explicitly phase-space covariant and avoids solving the constraints, providing a rigorous bridge between Dirac-bracket quantization and Fedosov quantization on $\Sigma$, along with an alternative formulation via first-class constraints on ${\bf V}(\mathcal M)$ and a total BRST charge.
Abstract
We propose an explicit construction of the deformation quantization of the general second-class constrained system, which is covariant with respect to local coordinates on the phase space. The approach is based on constructing the effective first-class constraint (gauge) system equivalent to the original second-class one and can also be understood as a far-going generalization of the Fedosov quantization. The effective gauge system is quantized by the BFV-BRST procedure. The star product for the Dirac bracket is explicitly constructed as the quantum multiplication of BRST observables. We introduce and explicitly construct a Dirac bracket counterpart of the symplectic connection, called the Dirac connection. We identify a particular star product associated with the Dirac connection for which the constraints are in the center of the respective star-commutator algebra. It is shown that when reduced to the constraint surface, this star product is a Fedosov star product on the constraint surface considered as a symplectic manifold.
