# Bootstrapping gauge theories (QCD)

- Institution: CERN
- Department: TH String Theory Seminar
- Speaker: Yifei He
- Year: 2023
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3001564)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

We consider asymptotically free gauge theories with gauge group SU(Nc) and Nf quarks with mass mq << LambdaQCD that undergo chiral symmetry breaking and confinement. We propose a bootstrap method to compute the S-matrix of the pseudo-Goldstone bosons (pions) that dominate the low energy physics. For the important case of Nc = 3, Nf = 2, a numerical implementation of the method gives the phase shifts of the S0, P1 and S2 waves in good agreement with experimental results. The method incorporates gauge theory information (Nc, Nf, mq, LambdaQCD) by using the form-factor bootstrap recently proposed by Karateev, Kuhn and Penedones together with a finite energy version of the SVZ sum rules. At low energy we impose constraints from chiral symmetry breaking. The only low energy numerical inputs are the pion mass and the quark and gluon condensates. Based on 2309.12402 with Martin Kruczenski. .

0:00:00 Slide 1

0:01:52 Slide 2

0:03:14 Slide 3

0:04:31 Slide 4

0:06:20 Slide 5

0:07:37 Slide 6

0:09:15 Slide 7

0:10:54 Slide 8

0:12:08 Slide 9

0:14:01 Slide 10

0:15:40 Slide 11

0:17:19 Slide 12

0:18:37 Slide 13

0:20:13 Slide 14

0:23:08 Slide 15

0:24:39 Slide 16

0:26:28 Slide 17

0:28:07 Slide 18

0:29:23 Slide 19

0:30:50 Slide 20

0:32:08 Slide 21

0:33:47 Slide 22

0:35:30 Slide 23

0:39:29 Slide 24

0:41:19 Slide 25

0:42:31 Slide 26

0:44:26 Slide 27

0:46:30 Slide 28

0:48:18 Slide 29

## Lectures

1. [Bootstrapping gauge theories (QCD)](https://invisiblenetwork.ai/learn/cern/3001564/b07b53ae08b3), 52 min (CERN's player)