# Introduction to field theory

- Institution: CERN
- Department: CERN Academic Training Lecture
- Speaker: Ronald H P Kleiss
- Year: 2001
- Level: Graduate
- Language: English
- Subjects: Physics
- Source: [CERN](https://videos.cern.ch/record/3000792)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Tweens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Starting from the notion of path integrals as developed by Feynman, we discuss field theory in zero spacetime dimensions. The concepts of perturbation expansions, connected amplitudes, Feynman diagrams, classical solutions, renormalization and the effective action are developed. The model is extended to four spacetime dimensions, and the full Feynman rules for relativisitc scalar theory derived. The S matrix and the concept of unitarity are discussed, leading to the amputation rules for S matrix elements from considerations of unitarity. The rules are extended to include particles with spin-1/2 and spin-1. The high-energy behaviour of the theory is discussed as a method to derive the gauge symmetry of the various models..

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## Lectures

1. [Introduction to field theory](https://invisiblenetwork.ai/learn/cern/3000792/8f8a236a1c56), 1 h 51 min (CERN's player)