Light scalars, analytical ππ scattering amplitude, the Roy equations, and chiral expansion

We build up the ππ scattering amplitude with regular analytical properties in the s complex plane. This amplitude is used to describe simultaneously the data on the ππ scattering, the ϕ→π0π0γ decay, and the reaction. The chiral shielding of the σ(600) meson and its mixing with the f0(980) meson are also taken into account. The amplitude in the range also agrees with results, obtained on the base of the chiral expansion, the dispersion relations, and the Roy equations. The analysis agrees with the four-quark nature of the σ(600) and f0(980) mesons.