| Summary: | Meson-meson interaction amplitudes especially ππ scattering amplitudes are often used incorrectly. It also applies to parameters of the σ meson. These causes two significant problems: threshold behavior and position of the σ pole which is suspicious. We modified multichannel S- and P- wave amplitudes for the ππ scattering, using dispersion relations with imposed crossing symmetry condition. The amplitudes are modified in the low-energy region to improve their consistency with experimental data and the dispersion relations. Agreement with data is achieved for both amplitudes from the threshold up to 1800 MeV and with dispersion relations up to 1100 MeV. Consequences of the applied modifications, e.g. changes of the S-wave lowest-pole positions, are presented.
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