Prog. Theor. Phys. Vol. 6 No. 3 (1951) pp. 441-442

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Note on Some Calculations in Quantum Field Theory

Department of Physics, Columbia University, New York, U.S.A.

(Received June 13, 1951)

URL : http://ptp.ipap.jp/link?PTP/6/441/
DOI : 10.1143/PTP.6.441

J. Yukawa and H. Umezawa, Prog. Theor. Phys. 6 (1951), 112[PTP].
R. P. Feynman, Phys. Rev. 56 (1939), 340[APS].
A. Pais and S. T. Epstein, Rev. Mod. Phys. 21 (1949), 445[APS].
In applying this result will be interested in < ∂H/∂µ >_VAC+1 - < ∂H/∂µ>_VAC, whence additive C numbers in H will play no role.
This subtraction of the vacuum current is implicitly implied in all calculations made with these theories since, in the language of Feynman diagrams, one always omits diagrams in which a point connects directly with itself.
See F. J. Dyson, Phys. Rev. 75 (1949), 486[APS].
If one would include such diagrams then, of course, most quantitative results would be changed.
J. Schwinger, Phys. Rev. 75 (1949), 651[APS].
K. Sawada, Prog. Theor. Phys. 5 (1950), 236[PTP].