# Spontaneous Breaking of Restricted Weyl Symmetry in Pure R^2 Gravity

- Institution: CERN
- Department: TH institutes
- Speaker: Ariel Edery
- Year: 2019
- Language: English
- Subjects: Physics, Astronomy and space
- Source: [CERN](https://videos.cern.ch/record/3001834)
- 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)

Recent work has shown that pure R^2 gravity (i.e. R^2 gravity with no extra R term) has a symmetry that is larger than scale symmetry and smaller than full Weyl symmetry. This has been dubbed restricted Weyl symmetry as it involves a Weyl transformation where the conformal factor has a constraint. Most importantly, this symmetry is spontaneously broken when the vacuum (background spacetime) has a non-zero Ricci scalar. In this case, the theory can be shown to be equivalent to Einstein gravity with non-zero cosmological constant and a massless scalar field. The massless scalar field is identified as the Goldstone boson of the broken sector. In spontaneously broken theories, the original symmetry of the Lagrangian is realized as a shift symmetry of the Goldstone bosons. We show that this is the case also here. The unbroken R=0 sector is completely different and has no connection to Einstein gravity..

0:00:00 Slide 1

0:00:35 Slide 2

0:01:55 Slide 3

0:02:24 Slide 4

0:03:30 Slide 5

0:04:06 Slide 6

0:04:10 Slide 7

0:04:17 Slide 8

0:04:55 Slide 9

0:05:18 Slide 10

0:05:22 Slide 11

0:07:39 Slide 12

0:07:43 Slide 13

0:07:53 Slide 14

0:09:00 Slide 15

0:09:08 Slide 16

0:09:27 Slide 17

0:10:47 Slide 18

0:11:18 Slide 19

0:13:04 Slide 20

0:13:19 Slide 21

0:13:56 Slide 22

0:14:36 Slide 23

0:15:49 Slide 24

0:18:42 Slide 25

0:21:42 Slide 26

0:23:33 Slide 27

0:23:37 Slide 28

0:23:51 Slide 29

0:23:55 Slide 30

## Lectures

1. [Spontaneous Breaking of Restricted Weyl Symmetry in Pure R^2 Gravity](https://invisiblenetwork.ai/learn/cern/3001834/8858e15e2fb2), 25 min (CERN's player)