S-matrix approach to two-pion production in e^+e^- annihilation and tau decay

Abstract

Based on the S-matrix approach, we introduce a modified formula for the ${\pi }^{\pm }$ electromagnetic form factor which describes very well the experimental data in the energy region $2m_{\pi }\le \sqrt{s}\le 1.1$ GeV. Using the CVC hypothesis we predict $B(\text{tpp})=(24.75\pm 0.38)\%$, in excellent agreement with recent experiments.

Comments: Latex, 10 pages, submitted to Phys. Rev. D