I am an physics undergrad in my pre-final year. Recently, I tried learning some QFT (from the likes of Peskin and Schroeder’s 1st 4 chapters, David tong etc.) and got interested in it’s working in a condensed matter setting. As it happens, listening to broad applications of QFT in CMP got me interested in learning about Keldysh field theory and am curious to see how it handles non-eqm situations. Currently I am stuck about charting a proper path/topics list that can help me reach Keldysh field theory in a proper manner. The only resource I have seen as such are ArviX articles which are quite inaccessible for me.
So I am asking about the necessary topics/chapters required to learn Keldysh Field theory. I’ve done some path integrals and am starting to know about imaginary time calculations. But I’ve no idea how exactly to proceed (another answer on stackexhange regd the resources is quite useful, but that assumes some pre-requisite, I wanted if a broad list of topics could be highlighted to reach there). Any resources/specific topics would be highly welcome.
As per my background - I have taken course work in Quantum mechanics (scattering/perturbation and relativistic) and am currently taking a course in solid state physics and stat mech. Ig some understanding of material here (i.e. coursework) would be pre-requisite, but till now following Negele and Orland’s book for the 1st couple of chapters, I’ve managed to build up whatever I need on the go. Hoping for suggestions!