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

A. Bernicha·G. Lopez Castro·J. Pestieau
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Abstract

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

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A. Bernicha, G. Lopez Castro, J. Pestieau. 1995-10-27. S-matrix approach to two-pion production in e^+e^- annihilation and tau decay. https://doi.org/10.1103/physrevd.53.4089

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