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Description
Hadrons are composite particles composed of quarks bound by the strong interaction and are conventionally classified into baryons ($qqq$), consisting of three quarks, and mesons ($q\bar{q}$), consisting of a quark-antiquark pair. In recent years, however, a series of discoveries of exotic hadrons that cannot be explained within the conventional hadron classification scheme has made them an important subject in hadron physics.
Among them, $T_{cc}(3875)^{+}$, reported by the LHCb experiment in 2022,
has attracted considerable attention as a genuinely exotic hadron because it possesses quantum numbers that cannot be realized within the conventional hadron classification. As a result, studies of exotic hadrons have become increasingly active.
Although no unified understanding of the internal structure of exotic hadrons has yet been established, the hadronic molecular picture has emerged as one of the most promising candidates because many of these states appear near the corresponding hadronic thresholds. In this picture, understanding hadron-hadron interactions is of central importance.
While information on hadron-hadron interactions has recently become available through approaches such as lattice QCD and femtoscopy,
theoretical conventional meson-exchange models still face limitations in describing the strong repulsive structure in the short-range region. Motivated by the suggestion that quark degrees of freedom become dominant at short distances, this study aims to investigate hadron-hadron interactions using the quark cluster model, which explicitly incorporates quark degrees of freedom, and to establish the corresponding theoretical framework.
Furthermore, we analyzed hadron-hadron interactions for the $\Omega\Omega$, $\Omega_{ccc}\Omega_{ccc}$, and $\Omega_{bbb}\Omega_{bbb}$ systems and confirmed the effects of quark degrees of freedom in the short-range region. By performing a systematic analysis, we also investigated the dependence on the quark mass.