QCD Organization of Exotic Hadrons Beyond Conventional Configurations

Determine the organizing principles of Quantum Chromodynamics that govern hadronic matter beyond conventional quark–antiquark mesons and three-quark baryons, including the structure and formation mechanisms of multiquark states such as tetraquarks and pentaquarks.

Background

The paper studies heavy-flavor fragmentation into fully heavy tetraquarks using the TQ4Q1.1 fragmentation-function sets within an NRQCD-based framework and threshold-consistent DGLAP evolution. This provides a controlled setting to connect perturbative short-distance production with nonperturbative hadronization inputs encoded in long-distance matrix elements.

In motivating the work, the authors emphasize that exotic hadrons—such as tetraquarks and pentaquarks—challenge current understanding of confinement and hadronization. They explicitly highlight that how QCD organizes matter beyond conventional quark–antiquark and three-quark configurations remains an open issue, which the presented framework aims to help address by supplying predictive fragmentation inputs and uncertainty quantification.

References

A key open question in hadron physics concerns how QCD organizes matter beyond the conventional quark–antiquark and three-quark configurations.

— Heavy-Flavor Fragmentation: The QCD Portal to Exotic Matter  (2604.01867 - Celiberto, 2 Apr 2026) in Section 1 (Introduction)

Whether QCD produces both the required deep binding and the required suppression remains an open dynamical question.

— Alpha-Core Breakup in the Strong Decay of \({}_{ΛΛ}^{6}\mathrm{He}\) to a Deeply Bound \(H\) Dibaryon  (2609.17117 - Shahrbaf et al., 15 Sep 2026) in Section I, Introduction

Unraveling the genuine nature of these resonances, whether they are compact multiquark states, hadronic molecules, hybrids, or admixtures thereof, across both meson and baryon systems is therefore crucial for mapping out the effective degrees of freedom of QCD in the low-energy domain and remains one of the foremost open questions in hadron spectroscopy.

— A High Performance Partial Wave Analysis Framework for Hadron Spectroscopy  (2608.25963 - Xiang et al., 26 Aug 2026) in Section 1, Introduction