Book contents
- Frontmatter
- Dedication
- Contents
- Introduction
- PART I Basics
- Part II Spin
- Part III Interactions
- 11 Perturbation Theory
- 12 Scattering, the Scattering Matrix and Cross-Sections
- 13 The Scattering Matrix in Perturbation Theory
- 14 Interacting Quantum Fields
- Part IV Renormalization
- Part V Complements
- Solutions to Selected Exercises
- Reading Suggestions
- References
- Index
11 - Perturbation Theory
from Part III - Interactions
Published online by Cambridge University Press: 22 February 2022
Book contents
- Frontmatter
- Dedication
- Contents
- Introduction
- PART I Basics
- Part II Spin
- Part III Interactions
- 11 Perturbation Theory
- 12 Scattering, the Scattering Matrix and Cross-Sections
- 13 The Scattering Matrix in Perturbation Theory
- 14 Interacting Quantum Fields
- Part IV Renormalization
- Part V Complements
- Solutions to Selected Exercises
- Reading Suggestions
- References
- Index
Summary
We give a brief and basic introduction to perturbation theory. The main idea is to attempt to consider the situation of interest as a small perturbation of a simpler situation (which can be understood completely), and in particular to consider a system with a weak interaction as a perturbation of a non-interacting system. We develop the interaction picture, which allows approximating the time-evolution of an interacting system by the partial sums of the Dyson series, a fundamental tool for the sequel. We illustrate these ideas on a rudimentary model of the interaction of electrons and “photons”.
- Type
- Chapter
- Information
- What Is a Quantum Field Theory? , pp. 299 - 321Publisher: Cambridge University PressPrint publication year: 2022