sigma and f_0(980) substructures from gamma-gamma to pi-pi, J/psi, phi radiative and D_s semi-leptonic decays

Understand

Using an improved "analytic K-matrix model", we reconsider the extraction of the sigma/f_0(600) and f_0(980) gamma-gamma widths from gamma-gamma to pi-pi scatterings data of Crystal Ball and Belle.

• Our main results are summarized in Tables 3 and 4.
• The averaged sigma "direct width" to gamma-gamma is 0.16(3) keV which confirms a previous result of [1] and which does neither favour a large four-quark (diquark-antidiquark) nor a molecule nor a pure \bar qq component.
• The "direct width" of the f_0(980) of 0.28(2) keV is much larger than the four-quark expectation but can be compatible with a \bar ss or gluonium component.