We show that the requirement of coordinate invariance of perturbatively defined quantum-mechanical path integrals in curved space leads to an extension of the theory of distributions by specifying unique rules for integrating products of distributions. The rules are derived by using equations of motion and partial integration, while keeping track of certain minimal features stemming from the unique definition of all singular integrals in 1 - ∊ dimensions. Our rules guarantee complete agreement with much more cumbersome calculations in 1 - ∊ dimensions where the limit ∊ → 0 is taken at the end. In contrast to our previous papers where we solved the same problem for an infinite time interval or zero temperature, we consider here the more involved case of finite-time or temperature amplitudes.
Reparametrization invariance of perturbatively defined path integrals. II. integrating products of distributions
