Calculation of Regge Trajectories of Strange Resonances and Identification of the $K_0^*(800)$ as a Non-ordinary Meson

Abstract

We review how the Regge trajectory of an elastic resonance can be obtained just from its pole position and coupling, using a dispersive formalism. This allows us to deal correctly with the finite widths of resonances in Regge trajectories. In this way, we can calculate the Regge trajectories for the K* (892), K_1(1400) and K_(0)^(*)(1430), obtaining ordinary linear Regge trajectories, expected for qq resonances. In contrast, for the K_(0)^(*)(800) meson, the resulting Regge trajectory is non-linear and with much smaller slope, strongly supporting its non-ordinary nature.