2

For a standard set of Feynman rules (following in-out formalism) in momentum space, extracted from a generally given Lagrangian, is there a generic algorithm for converting them into the Feynman rules (following in-in formalism) in momentum space? What changes one must make for such conversion of rules for the propagators and vertices in momentum space?

Qmechanic
  • 201,751
NovoGrav
  • 43

1 Answers1

2

Yes, the main points are that the field content gets doubled up, and that the Feynman propagators are replaced with e.g. retarded and advanced propagators. For details, see e.g. Refs. 1-4.

References:

  1. R.D. Jordan, Phys. Rev. D 33 (1986) 444.

  2. C.R. Galley & M. Tiglio, arXiv:0903.1122 ; chap. III.

  3. M. Levi, arXiv:1807.01699; p. 49-50.

  4. G.U. Jakobsen, G. Mogull, J. Plefka & B. Sauer, arXiv:2207.00569; chap. 2 p. 10.

Qmechanic
  • 201,751
  • Hello, thank you very much for the references. For calculating the integrals involving retarded and advanced propagators you mentioned about, is there any other references you could provide for learning it from scratch? – NovoGrav Sep 06 '22 at 20:32
  • Perhaps this? – Qmechanic Sep 07 '22 at 06:10