All Possible Symmetries of the S Matrix

Phys. Rev. 159, 1251 – Published 25 July 1967
Sidney Coleman and Jeffrey Mandula


We prove a new theorem on the impossibility of combining space-time and internal symmetries in any but a trivial way. The theorem is an improvement on known results in that it is applicable to infinite-parameter groups, instead of just to Lie groups. This improvement is gained by using information about the S matrix; previous investigations used only information about the single-particle spectrum. We define a symmetry group of the S matrix as a group of unitary operators which turn one-particle states into one-particle states, transform many-particle states as if they were tensor products, and commute with the S matrix. Let G be a connected symmetry group of the S matrix, and let the following five conditions hold: (1) G contains a subgroup locally isomorphic to the Poincaré group. (2) For any M>0, there are only a finite number of one-particle states with mass less than M. (3) Elastic scattering amplitudes are analytic functions of s and t, in some neighborhood of the physical region. (4) The S matrix is nontrivial in the sense that any two one-particle momentum eigenstates scatter (into something), except perhaps at isolated values of s. (5) The generators of G, written as integral operators in momentum space, have distributions for their kernels. Then, we show that G is necessarily locally isomorphic to the direct product of an internal symmetry group and the Poincaré group.


  • Received 16 March 1967
  • Published in the issue dated July 1967

© 1967 The American Physical Society

Authors & Affiliations

Sidney Coleman* and Jeffrey Mandula

  • Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts

  • *Alfred P. Sloan Research Fellow.
  • National Science Foundation Postdoctoral Fellow.

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