The Constraints of Unitary on $\pi \pi$ Scattering Dispersion Relations

Jianyang He, Z. G. Xiao, H. Q. Zheng

A new dispersion relation for the partial wave $\pi \pi$ scattering $S$ matrix is set up. Using the dispersion relation we generalize the single channel unitarity condition, $S{S}^{+}=1$, t…