Pauli wants to write first to Lee before the proposed paper by Pauli and Källén is written. He writes on a definition of a "ghost state". He expresses doubts about the Tamm-Dancoff approximation in the case of more general systems. He makes some mathematical remarks.
Pauli, WolfgangPauli thanks Källén for the manuscript. He writes about the Tamm-Dancoff method and some known negative attitude towards it. Small changes in the manuscript and the re-writing of the appendix.
Pauli, WolfgangPauli has some more suggestions for minor changes in the paper.
Pauli, WolfgangPauli replies to Källén's letter of the 10 March 1955. He suggests destroying the Lorentz invariance through the cut-off of the interaction energy in momentum-space. He writes on the validity of Born's approximation.
Pauli, WolfgangPauli writes on a paper by Bosco and Fubini "on the mathematical structure of the charged scalar meson theory". He talks about the progress of the work by Lehmann and Jost and about the CERN meeting.
Pauli, WolfgangPauli writes about a report from the USA by Jost that Bogoljubow has advanced more than anybody else in the mathematics of dispersion relations.
Pauli, WolfgangPauli sends forms to be filled out for CERN.
Pauli, WolfgangPauli encloses a letter by Heisenberg and asks Källén to write to him.
Pauli, WolfgangPauli expresses his doubts whether Källén's mathematics has anything to do with physics. He talks about Heisenberg's approach to the problem of field theory.
Pauli, WolfgangPauli talks about the progress made by Taylor in Princeton and Bogoljubov in dispersion relations and he writes about the article for the Springer Handbuch.
Pauli, Wolfgang