Quarks in the nucleus are bound by the strong force and cannot be isolated, yet high-energy experiments showed quarks behaving almost freely. The laureates analyzed Quantum Chromodynamics (QCD), noting that gluons interact with each other. They proved that the coupling constant decreases with increasing energy—the beta function is negative—so quarks feel weaker forces when very close (asymptotic freedom) and much stronger forces when farther apart, causing confinement. This settled outstanding puzzles and helped complete the Standard Model. The result underpins modern particle-accelerator design and simulations of the early universe.

The heart of the work is the derivation of the QCD beta function β(g)=−(11−2N_F/3)g^3/(16π^2)+…, which is negative for three colours (N_c=3) as long as the number of quark flavours N_F≤16. A negative beta function leads to a logarithmic decrease of the strong coupling α_s(Q^2) with energy, naturally explaining the scaling seen in deep-inelastic scattering (DIS). At low energies α_s diverges, signalling confinement where perturbation theory breaks down. Non-perturbative tools such as lattice QCD were later developed to compute hadron masses and structure from first principles. Asymptotic freedom also revitalised renormalisation of electroweak gauge theories, motivated coupling-constant unification studies and underlies research on high-temperature QCD plasma in the early universe and heavy-ion collisions.

In their 1973 PRL papers Gross & Wilczek and Politzer computed the one- and two-loop β-function for SU(3)_c gauge theory, obtaining β_0=(11−2N_F/3)/(4π)^2>0 and thus α_s(Q^2)=1/(β_0 ln(Q^2/Λ_QCD^2)). Operator-product expansion and the Altarelli–Parisi evolution predicted the logarithmic scaling violations observed in DIS at SLAC and CERN. The angular distribution of gluon radiation in three-jet events, treated via eikonal approximations, was validated at PETRA/PEP. The high-temperature limit g*≃37 informed baryogenesis models using the QCD equation of state. Asymptotic freedom remains central to SU(N) large-N analyses, non-conformal perturbations in AdS/CFT, and evaluations of Landau damping in the QCD color-superconducting phase diagram.