$a_0(980)$ as a companion pole of $a_0(1450)$

Abstract

Light scalar hadrons are often understood as dynamically generated resonances. These arise as `companion poles' in the propagators of $q\bar{q}$ seed states when accounting for meson-loop contributions to the self-energies of the latter. Following this idea, we demonstrate that for the scalar--isovector state $a_0(1450)$ the full one-loop propagator has two poles: a pole of the seed state $a_0(1450)$ and a companion pole corresponding to $a_0(980)$. The positions of these poles are studied by varying the relative coupling strength between the non-derivative and derivative parts of the interactions.

Comments: 8 pages, 1 figure, prepared for proceedings of "The 8th International Workshop on Chiral Dynamics", Pisa, Italy, June 31 - July 3, 2015