# The Strong Interaction at 50 Years: less Puzzling, more Rich, and still Mysterious

- Institution: CERN
- Department: Theory Colloquia
- Speaker: Iain Stewart
- Year: 2025
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3022753)
- 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)

The strong interaction is described by a remarkable theory called Quantum Chromodynamics (QCD), a quantum field theory that is fully consistent at all distance scales and that gives rise to interesting emergent phenomena. It plays a crucial role in a variety of important physical processes, from binding together quarks and gluons in the proton, to the evolution of a hot-plasma of matter in the early universe, to producing streams of collimated particles called jets in high energy collisions. In this talk I will review what we have learned about QCD and its phenomena in the fifty years since its inception, as well as discussing the important role that control of QCD effects have on measuring the fundamental parameters of the standard model of particle and nuclear physics. To highlight the mysteries of QCD that remain unsolved, I will describe a top-10 list of important open questions.

This seminar is part of the conference "Parton Showers and Resummation" (https://indico.cern.ch/event/1487647) .

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## Lectures

1. [The Strong Interaction at 50 Years: less Puzzling, more Rich, and still Mysterious](https://invisiblenetwork.ai/learn/cern/3022753/7ddacaff7e57), 1 h 9 min (CERN's player)