The most correct ρ0(770) meson mass and width values

By application of the pion electromagnetic form factor and also the P-wave isovector ππ scattering phase shift parametrizations, following from the first principles, like unitarity and analyticity, for a description of the corresponding accurate data, it is clearly demonstrated that the ρ0(770) meson mass and width values obtained by the Gounaris-Sakurai model in a description of the same data can not be accepted as correct ones.

Fully solvable mathematical scheme in finding out the right mass and width values of f0(500) and ρ0(770) mesons

Starting from the phase representations with one subtraction of the pion scalar-isoscalar and vector-isovector charged pion electromagnetic form factor and exploiting the most accurate information on the S-wave isoscalar and the P-wave isovector ππ scattering phase shifts, respectively, to be obtained from the existing inaccurate experimental data by means of the Garcia- Kamiński-Peláez-Yndurain Roy-like equations with an imposed crossing symmetry condition, in the framework of the so-called “fully solvable mathematical scheme” the most reliable values of the f0(500) and ρ0(770) meson mass and width are found.