Eur. Phys. J. A (2016) 52: 330
https://doi.org/10.1140/epja/i2016-16330-8

Regular Article - Theoretical Physics

Remarks on meson loop effects on quark models

¹ Forschungszentrum Jülich, Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, D-52425, Jülich, Germany
² Institute for Theoretical and Experimental Physics, B.Cheremushkinskaya 25, 117218, Moscow, Russia
³ National Research Nuclear University MEPhI, Kashirskoe highway 31, 115409, Moscow, Russia
⁴ Moscow Institute of Physics and Technology, 9 Institutsky lane, 141700, Dolgoprudny, Moscow Region, Russia

^* e-mail: i.hammer@fz-juelich.de

Received: 2 August 2016
Accepted: 24 October 2016
Published online: 15 November 2016

Abstract

We investigate the effect of meson loops on the spectrum of quark states. We demonstrate that in general quark states do not tend to get very broad if their coupling to the continuum increases, but instead they decouple from the latter in the large coupling limit. We ascribe this effect to the essentially nonperturbative unitarization procedure involved. In the meantime, some quark resonances behave very differently and demonstrate collectivity in the sense that their pole trajectories span a wide, as compared to the level spacing, region therefore acquiring contributions from multiple bare poles rather than from the closest neighbors. While the actual calculations are done within particular, very simplified models, it is argued that the findings might well be general.