Questions tagged [propagator]
propagator gives the probability amplitude for a particle to travel from one place to another in a given time, or to travel with a certain energy and momentum.
880 questions
3 votes
1 answer
80 views
Interpretation of real scalar field, its propagator and causality [duplicate]
It seems this has been discussed here previously (e.g this and this post), but I still feel uneasy. Essentially, I think it all boils down to the popular interpretation of the scalar field operator in ...
- 1,158
1 vote
1 answer
131 views
Microcausality in Fermions
We can show that for the Dirac field, the anti-commutator between the field and its adjoint vanishes for space-like separated points. However, for causality we need to show that the commutator instead ...
0 votes
0 answers
60 views
QED renomalization: Residue of the fermion propagator [duplicate]
I am trying to understand how one gets the residue of the fermion propagator and what its significance is. I suppose that a distinction between the field in the free theory and in the interacting ...
- 2,010
1 vote
2 answers
199 views
Green's function/propagator has 1 or 2 arguments?
I am having trouble to understand how do we define green's function just like that because previously it was just an inverse d'Alembertian and d'Alembertian only depends on 1 variable, however in this ...
- 63
3 votes
0 answers
182 views
Vacuum expectation value of any function in the free theory
I'm wondering whether the following expression for the free-field theory vacuum expectation value(VEV) of any function, $f(\phi(x))$, of a real scalar field $\phi(x)$ is correct or not: $$ \left \...
1 vote
0 answers
101 views
Kallen-Lehman Spectral Decomposition relation with Dyson Resummation
I am currently studying the Kallen-Lehman Spectral Decomposition and I have some doubts regarding how to relate it with the expression of the propagator as a geometric series of 1PI diagrams. ...
- 381
2 votes
1 answer
205 views
Difference between propagator and two-point correlation function in QFT
I am reading through Peskin and Schroeder and I am having some confusion in their derivation of the effective action being the generating functional of 1PI diagrams. In particular, they make a comment ...
- 279
4 votes
1 answer
268 views
Question about Srednicki's derivation of the Lehmann-Kallen form of the exact propagator
On page $108$, equation ($13.17$) of Srednicki's QFT textbook (draft version available online), he gives the Lehmann-Kallen form of the exact momentum-space propagator as $$\begin{equation} \tilde{\...