QCD Phases: Quark-Gluon Plasma as High-Temperature Confinement
Quark-gluon plasma is not deconfined: in τ, QGP is a state where the confinement scale exceeds the mean inter-quark distance (V.R151). QCD phase transitions are governed by defect-tuple inequality crossings (Book IV ch53); the B+C sector transition maps to the QCD deconfinement universality class (IV.R177).
Overview
The QCD phase diagram — the structure of strongly interacting matter at high temperature and density — is one of the open frontiers of nuclear physics. The widely taught picture is that above a critical temperature (~155 MeV at zero chemical potential) quarks and gluons are “deconfined” into a quark-gluon plasma. Book V ch29 (“Charge & Boundary Obstruction”) reframes this. V.R151 records that QGP is not actually deconfined: it is a state in which the confinement scale exceeds the mean inter-quark distance, so individual color-neutralization is not locally visible, but global confinement persists. QCD phase transitions in Book IV ch53 are governed by defect-tuple inequality crossings, and the B+C sector transition maps to the QCD deconfinement universality class (IV.R177).
Detail
Experimental heavy-ion programs at RHIC and LHC produced the quark-gluon plasma and showed it behaves as an almost-perfect fluid with low shear viscosity — a result difficult to reconcile with a weakly coupled deconfined gas. Lattice QCD produces a crossover transition at μ_B = 0 and predicts a possible critical endpoint at finite baryon chemical potential, but the structural ontology of the QGP state remains unclear. Book V ch29 (books/V-CategoricalMacrocosm/latex/sections/part04/ch29-charge-boundary-obstruction.tex lines 631-650) records: “Quark-gluon plasma is still confined” — the confinement scale in the high-temperature phase is larger than the mean inter-quark distance, so quarks appear quasi-free on short timescales but the global color-admissibility constraint is never violated. V.R151 formalizes this: QGP is high-temperature confinement, not deconfinement. Book IV ch53 (“Phase Transitions & Regimes”) organizes all phase transitions via defect-tuple inequality crossings in the (d₁, d₂, d₃, d₄) phase space; IV.R177 identifies the B+C sector (electroweak + strong) transition with the QCD deconfinement universality class. IV.D285 treats strong-gravity cross-coupling for QGP in curved spacetime (relevant for neutron-star mergers).
Result Statement
V.R151 + Book IV ch53 + IV.R177: Quark-gluon plasma is high-temperature confinement, not deconfinement. Phase transitions are defect-tuple inequality crossings; B+C transition maps to the QCD deconfinement universality class.