Regge trajectory of the f_0(500) resonance from a dispersive connection to its pole

Abstract

We report here our results on how to obtain the Regge trajectory of a resonance from its pole in a scattering process by imposing analytic constraints in the complex angular momentum plane. The method, suited for resonances that dominate an elastic scattering amplitude, has been applied to the {\rho}(770) and the f_0(500) resonances. Whereas for the former we obtain a linear Regge trajectory, characteristic of ordinary quark-antiquark states, for the latter we find a non-linear trajectory with a much smaller slope at the resonance mass. This provides a strong indication of the non-ordinary nature of the sigma meson.

Comments: 4 pages, 2 figures, to appear in the proceedings of the "Seventh International Symposium on Chiral Symmetry in Hadrons and Nuclei"