Two Shades of Quark Color: Parallel Canons across the Cold War Divide

TL;DR

Color emerged as two distinct constructs during the Cold War: a hidden three-valued label in Dubna's composite-hadron program and a local $SU(3)$ gauge charge in Yang–Mills theory leading to QCD. The paper investigates how these parallel narratives coexisted within divergent epistemic cultures—holist S-matrix/Regge approaches versus reductionist gauge theories—and uses the Fermilab E-36 case to illustrate how an observables-first program could yield robust forward-amplitude results before being sidelined by the rise of QCD. It shows that dualities and sum rules bridged micro and macro descriptions, enabling a domain-specific translation between residue-based color structure and colorless spectra, while later gauge-theory tests supplied decisive high-energy discriminants. The work advocates domain-sensitive pluralism in the historiography of high-energy physics, arguing that epistemic diversity matters for understanding how paradigm shifts unfold and why certain strands persist or fade beyond political contexts.

Abstract

The introduction of the color quantum number is conventionally narrated as a linear progression from the quark-model statistics paradox to quantum chromodynamics (QCD). This paper challenges that teleology by arguing that "color" emerged as two conceptually distinct constructs during the Cold War. The first, originating with Han and Nambu and culminating in QCD, conceived of color as a local gauge charge, the source of a fundamental force mediated by gluons. The second, developed at the Joint Institute for Nuclear Research (JINR) in Dubna, treated color as a hidden, three-valued label--a statistical and structural property within a composite, S-matrix-inflected hadron model. We trace these parallel narratives, linking the Dubna approach to a holist epistemology that prioritizes observable amplitudes and global constraints, and the QCD approach to a reductionist program grounded in micro-dynamics. A case study of Fermilab's E-36 experimental chain (1970--78) shows how an observables-first design-tuned to S-matrix and Regge constraints on forward elastic scattering--performed robustly within its natural domain but was ultimately discontinued amid declining theoretical interest and involvement. The subsequent hegemony of QCD retroactively projected its gauge-theoretic conception of color onto history, erasing this epistemic diversity. We conclude that the marginalization of Dubna's structural color was not merely a political outcome of the Cold War but a result of deep ontological and philosophical divergences, advocating for a domain-sensitive pluralism in the historiography of particle physics.