Bounds on the Pion's Charge Radius

Abstract

The strongest possible lower and upper bounds on the electromagnetic radius of the pion are derived in terms of the modulus of the timelike form factor. Numerical evaluation indicates that the radius is bounded above by the vector-dominance value and that the form factor will not behave as a "dipole" until $t={\mathrm{}\left(2E\right)\mathrm{}}^2>17\mathrm{}$ Ge${\mathrm{V}}^2$, if at all. The location and number of possible zeros of the form factor are discussed.