Gunnar Källén

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Gunnar Källén (born February 13, 1926 in Kristianstad , † October 13, 1968 near Hanover ) was a Swedish theoretical physicist who mainly worked on quantum field theory and elementary particle physics .

Life

Källén studied at Lund University with a doctorate under Torsten Gustafson in 1950. 1951/52 he was with Wolfgang Pauli in Zurich and then until 1957 at the theory department of CERN , which was then in Copenhagen . In 1957/58 he was at Nordita before becoming a professor in Lund. He became known through some fundamental work on quantum electrodynamics (QED) and quantum field theory (QFT) in the early 1950s. He showed that the formulation of the QED with renormalized charges also leads to inconsistencies (as also found by Pomerantschuk and Landau). With Pauli he showed in 1955 in the precisely solvable Lee model that because of such divergences, pathological behavior of the scatter matrix (non-unitaryity) occurs, which cannot be eliminated even by introducing states of negative norms (as considered at the time by Wolfgang Pauli, for example have been).

Källén's article on quantum electrodynamics in the Handbuch der Physik , originally written by Julian Schwinger , was also praised by Wolfgang Pauli, who is known to be more critical in this regard . A spectral representation (integral with principally observable data) of the QFT propagators is called a Källén-Lehmann representation .

Källén also worked on axiomatic quantum field theory . In 1958 he and Arthur Wightman wrote a paper on the analytic properties of the vertex function , which they viewed as a function of three complex Lorentz invariant variables, and showed holomorphism in a relatively large range of variables that they explicitly characterized. However, his preferences were more on the experimental basis, as his then very well-known textbook Elementary Particle Physics from 1964 showed, which has also been translated into German.

Källén died on October 13, 1968 while flying his own plane from Lund to Geneva to CERN , where he had been active since the 1950s. The plane crashed while attempting to land near Hanover; his wife Gunnel (who died a few years later) and the wife of a colleague survived.

In his obituary, Wightman stated: “I still remember the impact of the Helvetica Physica Acta paper of 1953. At that time I was trying to puzzle out the grammar of the language of quantum field theory, and here was Källén already writing poetry in the language ! ”

Publications

  • Mass and charge renormalization in QED without use of the interaction picture . In: Arkiv f. fysik , Volume 2, 1950, p. 187.
  • The definition of renormalization constants in Quantum Electrodynamics . In: Helvetica Physica Acta Volume 25, 1952, p. 417.
  • Charge renormalization and the identity of Ward . In: Helvetica physica acta Volume 26, 1953, p. 755.
  • On the magnitude of the renormalization constraints in QED . In: Math. Fys. Medd. Kongl. Dansk Vid. Selsk. , Volume 27, 1953, No. 12.
  • Old and new ideas in field theory . In: Hagen, Guralnik, Mathur (Ed.): Proceedings of the 1967 International Conference on Particles and Fields . Interscience.
  • Different approaches to field theory, especially quantum electrodynamics . In: 14th Solvay Conference 1967 .
  • Quantum Electrodynamics . In: S. Flügge (Ed.): Handbuch der Physik , Volume 5. 1958. Reprint Springer 1972.

literature

  • Cecilia Jarlskog (Ed.): Portrait of Gunnar Källén: A physics shooting star and poet of early quantum field theory . Springer 2014

Web links

Individual evidence

  1. ^ Källén, Anders Olof Gunnar - Author profile . INSPIRE-HEP . Retrieved July 19, 2019.
  2. ↑ Källén was the only Western scientist in Moscow in 1954 at a conference at which Landau and Pomeranschuk presented their results, compare Shirkov 1996, arxiv : hep-th / 9602024
  3. ^ Källén, Pauli: On the mathematical structure of TD Lee's model of a renormizable field theory . In: Math. Fys. Skrifter Kongl. Dansk Vid. Selskab . Volume 30, 1955, No. 7
  4. ↑ Källén, Wightman: The analytical properties of the vacuum expectation value of a product of three scalar fields . In: Math Fys. Skrifter Kongl. Dansk Vid. Selskab , Volume 1, 1958, No. 6
  5. ^ Källén: Elementary Particle Physics . BI university pocket book, Mannheim 1965 (English original 1964 by Addison-Wesley), 2nd edition with Jack Steinberger 1974.
  6. ↑ Erland Källén: My Father's Passion for Flying and His Mortal Accident . In: Cecilia Jarlskog (Ed.): Portrait of Gunnar Källén: a physics shooting star and poet of early quantum field theory . Springer Verlag, 2014, ISBN 978-3-319-00627-7 . doi : 10.1007 / 978-3-319-00627-7_31
  7. ^ A b Wightman: Gunnar Källén . In: Communications in mathematical physics , Volume 11, 1968, p. 181
personal data
SURNAME Källén, Gunnar
BRIEF DESCRIPTION Swedish physicist
DATE OF BIRTH February 13, 1926
PLACE OF BIRTH Kristianstad
DATE OF DEATH October 13, 1968
Place of death near Hanover