The Influence Of Different Form Factors On Meson Scattering

Quantum Chromodynamics (QCD) is widely believed to be the underlying theory of strong interactions, but it can not be used to solve the low energy region problem of non-perturbative directly. Thus, various QCD-inspired models are still needed to study the low energy hardon physics. The light Jp=0+scalar resonances, such as the σ resonance, have been in debates, since the width of σ resonance is very large, and many different masses are given by different experiments. The theoretical models also give many different results, the Particle Data Group (PDG) shows that the mass of σ resonance is between400-1200MeV.There are many models to explain the character of the σ resonance. The main models are the linear σ model, the non-linear σ model and the Unitarized Quark Model(UQM). By using the gauss form factor, the UQM model, which was proposed by Tornqvist, can explain the character of σ resonance which gives the σ mass is around500MeV, and the k mass is around760MeV, the model also gives other light scalar resonances quite well.In this work, in order to investigate the dependence of form factor, we will use three different form factors to replace the gauss form factor to further study the meson-meson scattering within the framework of UQM. We study the different isospin systems such as Kπ system with I=1/2, ππ system with I=0and πη system with I=1under UQM with different form factors. The results show that the σ resonance is vanished when the single pole form factor is used; when the other three form factors are used in UQM, the twelve different pole positions can be found on different Riemann Surfaces. We also find that the Kπ scattering phase shifts are consistent with the experimental data only below1.5GeV, however, the results are not good above the1.5GeV. It is also found that the three-pole form factor is better than other two form factors. All in all, the UQM results are are form factor dependent.