Identification of a scalar glueball

Area of Science:

• Particle Physics
• Quantum Chromodynamics
• Hadron Spectroscopy

Background:

• Understanding meson-meson S-wave interactions is vital for hadron spectroscopy.
• Existing models often neglect the strong coupled-channel dynamics in certain energy regions.

Purpose of the Study:

• To perform a coupled channel study of meson-meson S waves for isospin 0 and 1/2 up to 2 GeV.
• To develop a new approach for including multiple interaction channels with minimal parameters.
• To investigate the nature of scalar mesons and their relation to glueballs and quark states.

Main Methods:

• A novel coupled channel formalism was developed to analyze S-wave meson-meson scattering.
• The model incorporates numerous channels including pi pi, K Kbar, eta eta, sigma sigma, rho rho, omega omega, omega phi, phi phi, a1 pi, and pi pi.
• Resonance properties were extracted by fitting the model to experimental data.

Main Results:

• Coupled channel effects are significant, particularly for resonances in the 1.4-1.6 GeV region.
• All observed resonances with isospin 0 and 1/2 below 2 GeV were successfully generated.
• The f(0)(1710) and a significant component of the f(0)(1500) were identified as unmixed glueballs.
• A distinct pole, primarily associated with the f0(1370), was identified as a pure octet state.

Conclusions:

• The strong coupled channel dynamics are essential for accurately describing meson resonance properties.
• The findings support the existence of an unmixed scalar glueball, consistent with lattice QCD predictions.
• The study differentiates between glueball and quark-octet states within the scalar meson spectrum.