Multichannel Interaction Analysis of Scalar Mesons Below 1800 MeV

TL;DR

This paper analyzes scalar-isoscalar mesons below 1800 MeV using a multichannel unitary model, identifying resonances and their properties, and comparing results with experimental data.

Contribution

It introduces a multichannel analysis with separable interactions, revealing the structure and properties of scalar mesons and their relation to experimental resonances.

Findings

Identified scalar resonances f0(500), f0(980), and f0(1400).

Found two resonances between 1300 and 1500 MeV related to f0(1370) and f0(1500).

Compared theoretical results with experimental data on cross sections and branching ratios.

Abstract

Properties of scalar--isoscalar mesons in a mass range from pi-pi threshold up to 1800 MeV are analysed using an unitary model with separable interactions in three decay channels: pi-pi, K-anti K and an effective 2pi-2pi. Different solutions are obtained by fitting pi-pi and K-anti K data. Analytical structure of the meson-meson multichannel amplitudes is studied with a special emphasis on the important role played by the S-matrix zeroes. The dependence of the positions of S-matrix singularities on the interchannel coupling strength is investigated. Poles, located in the complex energy plane not too far from the physical region, are interpreted as scalar resonances: a wide f0(500), a narrow f0(980) and a relatively narrow f0(1400). In all our solutions two resonances, lying on different sheets, in the energy region between 1300 MeV and 1500 MeV are found. These states may be compared with the resonances f0(1370) and f0(1500) seen in the experiments at CERN. Total, elastic and inelastic channel cross sections, branching ratios and coupling constants are evaluated and compared with available data.