In the limit of $W_3$ symmetry proposed by Schwinger, selection rules and some relations among partial cross sections are derived through elementary calculations. One of the main results is that $\pi +N\to \Sigma +n$ pseudoscalar mesons, $\overline{K}+N\to \Sigma +n$ pseudoscalar mesons, and $\overline{K}+N\to \Xi +n$ pseudoscalar mesons are forbidden as well as their crossed reactions. Many of the selection rules and the relations derived here are badly violated at least in low-energy region. However, they should be tested with experimental data at much higher energies than those available at present.

• Received 22 May 1964

DOI:https://doi.org/10.1103/PhysRev.136.B272