Perturbative bosonization from two-point correlation functions

Here we address the problem of bosonizing massive fermions without making expansions in the fermion masses in both massive $QED_2$ and $QED_3$ with $N$ fermion flavors including also a Thirring coupling. We start from two point correlators involving the U(1) fermionic current and the gauge field. From the tensor structure of those correlators we prove that the U(1) current must be identically conserved (topological) in the corresponding bosonized theory both in D=2 and D=3 dimensions. We find an effective generating functional in terms of bosonic fields which reproduces those two point correlators and from that we obtain a map of the Lagrangian density $\bar{\psi}^{r} (i \partial / - m){\psi}^{r}$ into a bosonic one in both dimensions. This map is nonlocal but it is independent of the eletromagnetic and Thirring couplings, at least in the quadratic approximation for the fermionic determinant.