Two-pole structures in a relativistic Friedrichs–Lee-QPC scheme

Abstract A general appearance of two-pole structures is exhibited in a relativistic Friedrichs–Lee model combined with quark pair creation consistent manner. This kind structure could be found when $$q\bar{q}$$ q ¯ state couples to the open-flavor continuum S partial wave. We that many enigmatic states, such as $$f_0(500)/\sigma $$ f 0 ( 500 ) / σ , $$K_0^*(700)/\kappa K ∗ 700 κ $$a_0(980)$$ a 980 $$f_0(980)$$ $$D_0^*(2300)$$ D 2300 $$D_{s0}^*(2317)$$ s 2317 and X (3872), together another higher for each, all result from this structures. Furthermore, an interesting observation will contribute roughly total $$180^\circ 180 ∘ phase shift scattering process single channel approximation. scheme may provide more insights into understanding properties non- state. It also suggested common phenomenon which deserves studying both theoretical experimental perspectives.