Mechanism of quark confinement in Quantum Chromodynamics

Characterize the mechanism of confinement in Quantum Chromodynamics that binds quarks into hadrons at large distance scales where the strong coupling constant increases, and provide a detailed, predictive description of this process.

Background

The paper recounts the development from the static quark model to Quantum Chromodynamics (QCD), emphasizing experimental evidence from deep inelastic scattering at SLAC and the theoretical framework that followed. QCD exhibits asymptotic freedom at short distances, enabling precise calculations, but at larger distances the coupling becomes strong and quarks are confined into hadrons.

The author explicitly notes that while confinement is observed, the detailed mechanism behind it remains unresolved. This is a central open problem in strong-interaction physics and is highlighted here as an outstanding issue within the otherwise well-established QCD description of hadrons.

References

At larger distances, however, the coupling constant increases and leads to 'confinement' of quarks into hadrons, a mechanism not yet understood in detail.

— How quarks made their entrance into our worldview via cosmic rays and proton accelerators  (2401.07046 - Engelen, 2024) in Section "Quarks as 'static' building blocks versus quarks as dynamical particles"

Since additional quark--antiquark excitations from the vacuum incur an energetic cost and are therefore disfavored, we conjecture that the puncture is dominated by the minimal one-quark screening cloud, with the anti-diquark cloud providing the leading correction.

— Tracing Vacuum Hadronization with Conserved Currents  (2608.19708 - Ke et al., 20 Aug 2026) in Section 6, “Vacuum Hadronization and the Jet Gell-Mann–Nishijima Relation”