Discontinuities of kinematic factors at zero masses and related problems

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4 Scopus citations


We expalin why some kinematical factors are discontinuous when one of the masses vanishes. We derive the kinematic factors for general reactions involving one massless particle. The method can be easily extended to more than one massless particle. We use the crossing relations to rederive and generalize in a simple way the kinematical constraints at s=0 recently obtained by Stack. We give a general expression for the determinant of the regularized crossing matrix and discuss its applications.

Original languageEnglish
Pages (from-to)2375-2389
Number of pages15
JournalPhysical Review
Issue number5
StatePublished - 1 Dec 1969
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (all)


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