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Published October 25, 1968 | public
Journal Article Open

Kinematical constraints on helicity amplitudes


The kinematical constraints satisfied by helicity amplitudes are derived by two methods. One uses extra kinematical symmetries, which are present whenever there are constraints. The other uses the connection between M functions and helicity amplitudes. It is shown that the threshold and pseudothreshold constraints do not imply conspiracies between different Regge trajectories. The transitions between the different sets of s=0 constraints (which change when masses become equal) are described.

Additional Information

©1968 The American Physical Society. Received 22 April 1968. The author would like to thank Professor Steven Frautschi for stimulating this research, and Dr. Padmanabhan Babu, Dr. Lorella Jones, Dr. Claudio Rebbi, and Dr. Richard Slansky for helpful conversations. Work supported in part by the U.S. Atomic Energy Commission. Prepared under Contract No. AT(11-1)-68 for the San Francisco Operations Office, U.S. Atomic Energy Commission.


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