Tetraquark bound states in constituent quark models: Benchmark test calculations

Abstract

We investigate the tetraquark bound states that are manifestly exotic using three distinct few-body methods; Gaussian expansion method (GEM), resonating group method (RGM), and diffusion Monte Carlo (DMC). We refer to manifestly exotic states that do not involve a mixture with the conventional mesons through the creation and annihilation of $n\overline{n}$, where $n=u$, $d$. Our calculations are conducted with two types of quark models; the pure constituent quark model featuring one-gluon-exchange interactions and confinement interactions, and the chiral constituent quark model, supplemented by extra one-boson-exchange interactions. This study represents a comprehensive benchmark test of various few-body methods and quark models. Our findings reveal the superiority of GEM over RGM and DMC methods based on present implements for the tetraquark bound states. Additionally, we observe a tendency for the chiral quark model to overestimate the binding energies. We systematically explore the fully, triply, doubly, and singly heavy tetraquark states with ${J}^{P}={0}^{+},{1}^{+},{2}^{+}$, encompassing over 150 states in total. We successfully identify several bound states, including $[cc\overline{n}\overline{n}{]}_{{J}^{P}={1}^{+}}^{I=0}$, $[bb\overline{n}\overline{n}{]}_{{J}^{P}={1}^{+}}^{I=0}$, $[bc\overline{n}\overline{n}{]}_{{J}^{P}={0}^{+},{1}^{+},{2}^{+}}^{I=0}$, $[bs\overline{n}\overline{n}{]}_{{J}^{P}={0}^{+},{1}^{+}}^{I=0}$, $[cs\overline{n}\overline{n}{]}_{{J}^{P}={0}^{+}}^{I=0}$, and $[bb\overline{n}\overline{s}{]}_{{J}^{P}={1}^{+}}$, all found to be bound states below the dimeson thresholds.

Topics & Concepts