Calculation of Regge trajectories of strange resonances and identification of the K0*(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 $K^{\ast }(892)$, $K_1(1400)$ and $K_0^{\ast }(1430)$, obtaining ordinary linear Regge trajectories, expected for $q\bar{q}$ resonances. In contrast, for the $K_0^{\ast }(800)$ meson, the resulting Regge trajectory is non-linear and with much smaller slope, strongly supporting its non-ordinary nature.

To appear in the proceedings of Excited QCD 2016, Costa do Caparica, Portugal, March 6-12