nLab tadpole
Context
Algebraic Qunantum Field Theory
algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)
Concepts
quantum mechanical system, quantum probability
interacting field quantization
Theorems
States and observables
Operator algebra
Local QFT
Perturbative QFT
Contents
Idea
In perturbative quantum field theory a tadpole is a contribution to the S-matrix/scattering amplitude corresponding to a Feynman diagram which contains an edge that connects some vertex with itself.
Typically tadpoles are required to be absent. For instance the construction of time-ordered products in causal perturbation theory via the “star product” induced by the Feynman propagator (see there) implies that tadpoles are absent.
Examples
Related concepts
References
Discussion in context of causal perturbation theory/perturbative AQFT is in
- Kai Keller, around p. 30 of of Dimensional Regularization in Position Space and a Forest Formula for Regularized Epstein-Glaser Renormalization, PhD thesis (arXxiv:1006.2148)
Last revised on October 4, 2019 at 10:40:10. See the history of this page for a list of all contributions to it.