Algebraic Collapse, Modular Rigidity, and Sector Exclusion in Contractive Quantum Markov Semigroups: Structural Closure of the Canonical QMS Program

This paper establishes the structural closure layer of the canonical QMS–spectral program. Working entirely within the framework of uniformly continuous quantum Markov semigroups (QMS) on von Neumann algebras, the paper proves that strict contractivity, faithful invariant states, and complementary slackness at active constraints force a series of nontrivial structural consequences. The results do not assume spacetime geometry, field equations, or particle content. They are operator-theoretic consequences of contractive fixed-point dynamics. The principal structural results include: Algebraic collapse at the active constraint surface via a quantitative pinching gap: superpositions of fixed-point and transient components are excluded exactly, not merely asymptotically. Born-exponent rigidity: modular implementability and the Jordan–von Neumann parallelogram characterization force the unique Schatten exponent p = 2 within the unitarily invariant operator norm family. Recovery of the Born probability rule via Gleason’s theorem once Hilbert geometry is enforced. Strict directedness of the non-fixed-point sector induced by spectral gap and contraction. Primitive completeness: the fixed-point algebra is completely characterized by the commutant of the GKSL generator data; no additional independent structural primitive exists. Exact constraint count equal to eight under bidual independence. Minimal admissible carrier classification: symmetric bilinear structure is uniquely compatible with the constraint budget; linear and higher-arity carriers are excluded. Sector parameter exclusion via Osterwalder–Schrader measure positivity: the deformation parameter theta must vanish in order for Euclidean positivity and positive-norm Hilbert space reconstruction to hold. The paper proves that once strict contractivity is imposed on structural data, the fixed-point algebra, probability geometry, carrier structure, and admissible sector parameters are rigidly determined. This completes the structural closure layer of the five-part canonical QMS–spectral program: Construction layer – canonical spectral bridge and OS positivity. Rigidity layer – spectral compactness, Weyl invariance, and capacity constraints. Structural closure layer – algebraic collapse, modular rigidity, primitive completeness, and sector exclusion (this paper). Universal reduction theorem – reduction from minimal relativistic QFT assumptions to the canonical framework. Universality theorem – forcing of Einstein dynamics at leading order. The present work contains no phenomenological assumptions and introduces no adjustable parameters. All results follow from operator-algebraic fixed-point structure and contractive dynamics.