The Kinetic Constituent Mass: Relativistic Rotation of the ER String and the Origin of the Nucleon Core in Spin-Space (XVIII v4)

This paper separates and formalizes two distinct mass-energy regimes of the quark Einstein- Rosen (ER) dipole within the FCD-RBv4 pregeometric framework. The primordial formation regime determines the current (bare) quark masses and the inter-brane Compton scales. In contrast, the operating regime governs the three-dipole baryonic triplet. From the triple truncation point, the endpoints of the ER bridges rotate at highly relativistic speeds (v ≈ 0.999976c) in spin-space. We derive that this rotational kinetic energy generates the effective constituent mass scale (m const= M p/3 ≈ 312.8 MeV), which acts as the physical ’proton core.’ This pregeometric model is shown to resolve several long-standing questions without a dynamical gluon fie ld: (1) the ER bridge behaves as a single string under tension σ ≈ 0.99 GeV/fm, matching lattice QCD; (2) the relativistic rotation carries exactly one quantum of orbital angular momentum , which is halved to spin-1/2 by the two- brane anchoring; and (3) the up/down kinetic asymmetry naturally yields the correct sign and bare strong- sector magnitude of the neutron-proton mass difference (m d− m u≈ 2.51 MeV), corrected to 0.2% accuracy once electromagnetic self-energy structures are properly accounted for. We present the complete mathematical scaling and list experimental predictions.