Anders Olof Gunnar Källén (13 February 1926 in

Kristianstad Kristianstad (, ; older spelling from Danish language, Danish ''Christianstad'') is a Urban areas in Sweden, city and the seat of Kristianstad Municipality, Scania County, Sweden with 40,145 inhabitants in 2016. During the last 15 years, it has ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

– 13 October 1968 in

Hanover Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German state of Lower Saxony. Its 535,932 (2021) inhabitants make it the 13th-largest city in Germany as well as the fourth-largest city in Northern Germany ...

West Germany West Germany is the colloquial term used to indicate the Federal Republic of Germany (FRG; german: Bundesrepublik Deutschland , BRD) between its formation on 23 May 1949 and the German reunification through the accession of East Germany on 3 O ...

in a plane accident) was a leading Swedish

theoretical physicist Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimen ...

and a professor at

Lund University , motto = Ad utrumque , mottoeng = Prepared for both , established = , type = Public research university , budget = SEK 9 billion CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...

's theoretical division in Copenhagen, which then became the

Niels Bohr Institute The Niels Bohr Institute (Danish: ''Niels Bohr Institutet'') is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics. ...

. He also worked at

Nordita The Nordic Institute for Theoretical Physics, or NORDITA, or Nordita ( da, Nordisk Institut for Teoretisk Fysik), is an international organisation for research in theoretical physics. It was established as Nordisk Institut for Teoretisk Atomfys ...

1957–1958 and then began a professorship at Lund University. Källén's research focused on

quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and ...

and

elementary particle In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions ( quarks, leptons, an ...

physics. His developments included the so-called Källén–Lehmann representation of correlation functions in quantum field theory, and he made contributions to

quantum electrodynamics In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and spec ...

, especially in renormalizing. He also worked with the axiomatic formulation of quantum field theory, which led to contributions to the theory of functions of several complex variables. He collaborated on the Pauli–Källén equation. The

Källén function The Källén function, also known as triangle function, is a polynomial function in three variables, which appears in geometry and particle physics. In the latter field it is usually denoted by the symbol \lambda. It is named after the theoretical ...

is named after him. Källén worked for several years at the Bohr Institute. Källén was flying his own plane from

Malmö Malmö (, ; da, Malmø ) is the largest city in the Swedish county (län) of Scania (Skåne). It is the third-largest city in Sweden, after Stockholm and Gothenburg, and the sixth-largest city in the Nordic region, with a municipal populat ...

to CERN in

Geneva Geneva ( ; french: Genève ) frp, Genèva ; german: link=no, Genf ; it, Ginevra ; rm, Genevra is the List of cities in Switzerland, second-most populous city in Switzerland (after Zürich) and the most populous city of Romandy, the French-speaki ...

when it crashed in 1968. His two passengers, one of them his wife, survived the crash.

Bibliography

*G. Källén, ''Quantenelektrodynamik'', Handbuch der Physik (Springer-Verlag, Berlin, 1958) *G. Källén, ''Elementary Particle Physics'' (Addison-Wesley, Reading, Massachusetts, 1964) *G. Källén, ''Quantum Electrodynamics'' (Springer-Verlag, Berlin, 1972)
2013 pbk reprint

Bibliography

See also

References

Further reading