# Gauge theories from scattering amplitudes with minimal assumptions

- Institution: CERN
- Speaker: Clara Hernández García
- Year: 2026
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3020965)
- Licence: [CERN](https://copyright.web.cern)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

We revisit the emergence of a Yang-Mills symmetry in theories with massless spin 1 particles from fundamental physical properties of scattering amplitudes. In the standard proofs, some symmetry and reality properties of the coupling constants in three-point amplitudes are assumed. These properties cannot be justified using only three-point amplitudes but we show that they arise as consequences of the consistent factorization of four-particle amplitudes, for particular choices of the particle basis. This applies to self-interactions of massless spin 1 particles and also to their interactions with spin 0 and 1/2 particles. CP invariance is a derived property, not an additional assumption. The situation for gravity interactions is analogous and it is dealt with in the same fashion.

0:00:00 Slide 1

0:00:19 Slide 2

0:00:44 Slide 3

0:01:05 Slide 4

0:01:55 Slide 5

0:02:43 Slide 6

0:03:24 Slide 7

0:04:31 Slide 8

0:04:55 Slide 9

0:05:27 Slide 10

0:06:30 Slide 11

0:07:34 Slide 12

0:08:31 Slide 13r>

## Lectures

1. [Gauge theories from scattering amplitudes with minimal assumptions](https://invisiblenetwork.ai/learn/cern/3020965/86d750439d81), 10 min (CERN's player)