The PDL–QCD Boundary: Structural Derivation of the Proton–Electron Mass Ratio Correction and a Parameter-Free Conjecture for Newton's Constant

Within the Projective Dynamic Logo (PDL) framework, the bare proton-to-electron mass ratio is given by μ_PDL = R_tot/R_e = 11017/6, which overshoots the experimental value μ_exp = 1836.152673 by δμ = 0.013993. This paper identifies the structure of this residual and proposes a factorisation at the PDL–QCD boundary. We show numerically that δμ factorises as δμ = (155/11017)·(1 − 2Δm_iso/m_p) + O(47 ppm), where 155/11017 is the leading-order valence engagement amplitude of the PDL proton and Δm_iso = m_d − m_u is the QCD isospin mass difference. This factorisation yields the PDL prediction (m_d − m_u)_PDL = 2.532 MeV, at 0.040σ of the PDG 2024 central value. From this factorisation, we derive a closed-form conjecture for the primary coherence leakage parameter ε_G ∈ ℚ(√5), accurate to 17 ppm against CODATA 2022, which — if proved as an exact identity — would make Newton's gravitational constant G a fully combinatorial prediction of the proton quintuplet (24, 28, 930, 10087, 11017) with Δm_iso as the sole external input. The paper also predicts μ* = 1836.152670, matching experiment to 0.002 ppm, as a corollary of the conjecture. Steps (a) and (b) of the proof — establishing 155/11017 from PDL axioms and deriving the coefficient 2 structurally — are identified as open problems, resolved respectively in D29 and D30.