  Low-energy nuclear interactions have been extensively studied in the
framework of chiral effective field theory. The corresponding potentials have
been worked out using dimensional regularization to evaluate ultraviolet
divergent loop integrals. An additional cutoff is then introduced in the
nuclear Schr\"odinger equation to calculate observables. Recently, we have
shown that such a mixture of two regularization schemes violates chiral
symmetry when applied beyond the two-nucleon system and/or to processes
involving external probes. To solve this issue, three- and four-nucleon forces
as well as exchange current operators need to be re-derived using
symmetry-preserving cutoff regularization. While it is possible to introduce a
symmetry-preserving cutoff already in the effective chiral Lagrangian, the
appearance of high-order time derivatives of the pion field, caused by the
regulator, makes the standard Hamiltonian-based methods not well suited for the
calculation of nuclear potentials. Here, we propose a new approach to derive
nuclear interactions using the path integral method with no reliance on the
canonical quantization. To this aim, the interaction part of the action is
brought to an instantaneous form via suitably chosen nonlocal field
redefinitions. Loop contributions to the nuclear potentials are then generated
through the functional determinant, induced by the field redefinitions. We
discuss in detail the application of these ideas to the case of a regularized
Yukawa-type model of pion-nucleon interactions. Our new method allows to
perform a systematic quantum mechanical reduction within the quantum field
theory framework and opens the way for deriving consistently regularized
nuclear forces and current operators from the effective chiral Lagrangian.
