The sigma and f_0(980) from K_e4+pi-pi, gamma-gamma scatterings, J/psi, phi to gamma sigma_B and D_s to l nu sigma_B

TL;DR

This paper uses an improved analytic K-matrix model to analyze scattering data, extracting properties of sigma and f_0(980), and discusses their internal structure and production mechanisms in various decays.

Contribution

It provides new determinations of pole positions and widths of sigma and f_0(980) using an advanced analytic approach, clarifying their quark and gluon components.

Findings

Sigma has a large gluon component.

F_0(980) likely contains ar ss and/or gluon components.

Results favor a gluonium nature for sigma and a mixed composition for f_0(980).

Abstract

We extract the pole positions, hadronic and gamma-gamma widths of sigma and f_0(980, from pi-pi and gamma-gamma scattering data using an improved analytic K-matrix model. Our results favour a large gluon component for the sigma and a \bar ss or/and gluon component for the f_0(980) but neither a large four-quark nor a molecule component. Gluonium sigma_B production from J/psi, phi radiative and D_s semi-leptonic decays are also discussed.