https://doi.org/10.1140/epjc/s10052-022-10272-6
Regular Article -Theoretical Physics
Four-quark states with charm quarks in a two-body Bethe–Salpeter approach
1
Institut für Theoretische Physik, Justus-Liebig Universität Gießen, 35392, Giessen, Germany
2
Helmholtz Forschungsakademie Hessen für FAIR (HFHF), GSI Helmholtzzentrum für Schwerionenforschung, Campus Gießen, 35392, Giessen, Germany
b
christian.fischer@theo.physik.uni-giessen.de
Received:
10
December
2021
Accepted:
27
March
2022
Published online:
9
April
2022
We study the internal structure of a range of four-quark states with charm quark contributions using a two-body Bethe–Salpeter equation. Thereby, we examine charmonium-like states with hidden charm and quark content 
, open-charm states with quark content 
and all-charm states with 
. In particular we study the internal competition between meson–meson components and diquark–antidiquark components in the wave functions of these states. Our results indicate that the 
and the 
are predominantly 
states and that the recently discovered open-charm state 
is dominated by an internal 
component. In both cases the diquark components are negligible. For the all-charm state X(6900) with as yet unknown quantum numbers we identify candidates in the excitation spectra of 
and 
states. Furthermore, our framework serves to provide predictions for further, yet undiscovered open and hidden charm four-quark states.
© The Author(s) 2022
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Funded by SCOAP3
