Can anyone help me understand Matin-Siggia-Rose-deJensen formalism? To be more specific, I'm studying this paper, and in section 5, the authors go all about classical limit and the usage of MSRJD formalism, of which I have no familiarity. My main background has been towards Feynman Path integrals and a thermodynamics in the quantum regime (mainly non-equilibrium process). I would be glad if anyone can point out any reasonable reference to me, even though the authors give some references in the article, I am looking forward to finding some textbooks, videos, blogs or whatever can be of easier understanding.
Another issue that I have is to why one would go with this formalism to find classical limit? I would imagine that some expansion, depending on $\hbar$ as depicted in this question, would have shown a classical limit. Any help is welcome!
