Mp. Locher et al., PI-PI FINAL-STATE INTERACTION IN K-]PI-PI, PP-]PP-PI-PI, AND RELATED PROCESSES, Physical review. D. Particles and fields, 55(5), 1997, pp. 2894-2901
Final state interactions in the S-wave pi pi system (I=0,2) are reexam
ined on the basis of the Omnes-Muskhelishvili equation and the coupled
channel formalism. The contributions to the pion scalar form factor f
rom rho and f(2)(1270) exchange in the t channel and from the f(0)(980
) s-channel resonance are separately evaluated and the role of the non
trivial polynomial in the Omnes function in a coupled channel situatio
n is elucidated. Applications are made to K --> pi pi and pp --> pp pi
pi. It is found that the contribution from the f(0) resonance to the
form factor is strongly reduced by a nearby zero.