Unitarity and gluonic corrections to the pion form factor around the φ peak

The transition φ→π+π-, which is forbidden by the Okubo-Zweig-Iizuka rule and by isospin conservation, is discussed in the context of unitarity and quantum chromodynamics. The analysis reveals that basic aspects of these theoretical contexts may be clearly tested by a reasonably accurate measurement of σ(e+e-→π+π-) around the φ peak. © 1979 The American Physical Society.