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seen Jun 29 at 21:32

Jul
28
comment Renormalization, symmetries and freedom to choose counterterms
My problem is probably to see how 'symmetries' are respected in arbitrary Greens functions if I 'absorb' the counterterm rules in that for the basic Lagrangian. Surely my questions are very basic, but I might be a bit irritated because these concerns are largely irrelevant for the simple models treated in the literature.
Jul
28
comment Renormalization, symmetries and freedom to choose counterterms
Yes, I understand this. What I meant here is that the set of basic Feynman graphs (propagators and vertices) is taken to be the same as for the bare theory. This is because, as you say, the structure of the Lagrangian stays the same. Obviously the rules (analytic expressions) for the Feynman graphs are different, such that perturbative results computed based on the new rules are the same (possibly up to higher orders), as if I would take the rules for the basic Lagrangian plus that for the counterterms.
Jul
28
asked Renormalization, symmetries and freedom to choose counterterms
Apr
4
asked CP-symmetry and Ward identities and finite temperature
Nov
18
comment Unstable particles and quantum field theory
Concerning physical interpretations I think of modified decay laws, Quantum Zeno effect and so on. Things which are usually discussed for individual particles. How may such effects be extracted from the statistical Kadanoff-Baym description or how can I understand it in terms of ordinary relativistic quantum mechanics.
Nov
18
comment Unstable particles and quantum field theory
... merely searching for the connection to conventional quantum field theory and the optical theorem as well as physical interpretations.
Nov
18
comment Unstable particles and quantum field theory
Thank you. I am familiar with the Kadanoff-Baym equations. I am
Nov
17
asked Unstable particles and quantum field theory
Sep
7
awarded  Student
Sep
7
asked Validity of Cutkosky cutting rules for fermions
Sep
7
awarded  Supporter