**In honour of the memory of Oskar Klein, the Organizing Committee of the Oskar Klein Memorial Lectures every year invites a distinguished researcher to give a Memorial Lecture and to receive the Klein medal.**

### The 2022 Oskar Klein Memorial Lecture

*will be given by*

## Igor R. Klebanov

*with the title*

## Strong Interactions, Strings, and Extra Dimensions

### The lecture will take place on Thursday 19 May 2022 at 15.15 in the Oskar Klein Auditorium, AlbaNova.

* Abstract: In the 1950s and 60s, many strongly interacting particles (mesons and baryons) were discovered. String theory was originally invented to describe them, but in the early 70s Quantum Chromodynamics (QCD) emerged as the precise theory of the strong nuclear force. A quarter century later, it was understood that string theory and certain gauge theories akin to QCD are different descriptions of the same physics. I will review the relations between gauge theories and strings. The formation of QCD strings is a manifestation of the confinement of colored quarks and gluons. The Confinement is observed numerically using Lattice Gauge Theory, and the gauge/gravity duality has shed new light on it, but its analytic proof remains a deep unsolved problem in theoretical physics. I will conclude by discussing some surprises in lower-dimensional models for QCD*.

Oskar Klein (1894-1977) was 23 years old when he came to Niels Bohr in Copenhagen. He stayed there until 1931 at which time he became professor in theoretical physics at Stockhom University where he stayed until his retirement in 1962. Klein had a broad interest in various fields of physics but is perhaps best known for the Klein-Gordon equation and the Klein-Nishina equation. His attempts to unify general relativity and electromagnetism by introducing a five-dimensional space-time dates back to 1926 and is today known as Kaluza-Klein theory.

For a biography of Oskar Klein, please read here.