Regge trajectories of ordinary and non-ordinary mesons from their scattering poles.

Our results on obtaining the Regge trajectory of a resonance from its pole in a scattering process and from analytic constraints in the complex angular momentum plane are presented. The method, suited for resonances that dominate an elastic scattering amplitude, has been applied to the p(770), f₂(1270), f₀(1525) and f_o(500) resonances. Whereas for the first three we obtain linear Regge trajectories, characteristic of ordinary quark-antiquark states, for the latter we find a nonlinear trajectory with a much smaller slope at the resonance mass. We also show that if a linear trajectory with a slope of typical size is imposed for the fo(500), the corresponding amplitude is at odds with the data. This provides a strong indication of the non-ordinary nature of the sigma meson. [ABSTRACT FROM AUTHOR]