Overview
The gauge structure sub-programme answers a single central question. The non-injective projection $\Pi: \chi \to O$ selects admissible configurations from the relational substrate; its fibre $\Pi^{-1}(O_n)$ carries internal structure: which internal symmetry groups are preserved as invariants of admissible projection, and why are they precisely $\mathrm{U}(1)$, $\mathrm{SU}(2)$, and $\mathrm{SU}(3)$?
Define $G_\Pi$ as the group of fibre symmetries of $\Pi$ that preserve the admissibility constraints. The sub-programme establishes $G_\Pi = \mathrm{SU}(3) \times \mathrm{SU}(2) \times \mathrm{U}(1)$: the gauge group of the Standard Model is a forced output of admissibility, not a separate postulate. The sub-programme sits at the intersection of the foundational branch (axiomatic primitive and fibre structure) and the spectral admissibility branch (Weil representation, co-admissibility). It covers gauge group identification only; the derivation of Yang–Mills dynamics belongs to the gauge–gravity spectral stratification sub-programme.
The structural chain
$\Pi \simeq S^3 \;\Longrightarrow\; S^1 \hookrightarrow S^3 \to S^2 \;\Longrightarrow\; \mathrm{U}(1) \;\Longrightarrow\; \mathfrak{su}(2) \text{ from } \operatorname{Im}\mathbb{H} \;\Longrightarrow\; \mathrm{SU}(2) \;\Longrightarrow\; \mathrm{SU}(3).$
Three factors arise from distinct structural mechanisms: the $\mathrm{U}(1)$ phase symmetry of the Hopf fibre, whose winding number $w \in \pi_1(S^1) \cong \mathbb{Z}$ is the topological origin of electric charge ($q_{\mathrm{eff}} = w \cdot e$); the $\mathrm{SU}(2)$ rigidity forced by $\mathbb{H}$ as the minimal admissible associative non-commutative algebra, with $\dim_\mathbb{R} \operatorname{Im}\mathbb{H} = 3$ giving three internal directions and the O27 rigidity theorem forcing every admissible morphism to factor through $\mathfrak{su}(2)$; and the $\mathrm{SU}(3)$ symmetry of co-admissible colour triplets $\{V_c, V_{\omega c}, V_{\omega^2 c}\}$ for $q \equiv 1 \pmod 3$, established unconditionally on the colour-adapted Cayley graph (O31) and at the rank, averaged, and effective-exponent levels on the standard graph (O31–O32).
Papers of the sub-programme
$\mathrm{U}(1)$ phase fibre and charge quantisation.
- Foundation — identifies the projection fibre $\Pi^{-1}(O_n)$ with the Weil representation $V_\rho$ of $\mathrm{Heis}_3(\mathbb{Z}/q\mathbb{Z})$, carrying a canonical symplectic (hence phase) structure.
- TopologicalInvariants — classifies the admissible homotopy invariants of the projection fibre. Electric charge $q_{\mathrm{eff}} = w \cdot e$ from $\pi_1(S^1) \cong \mathbb{Z}$; absence of magnetic monopoles from $\pi_2(\mathcal{C}_{\mathrm{adm}}) = 0$ on the canonical model; projective chirality as orientation dependence of admissibility.
- SMchargemass — interprets mass, charge, and inertia as distinct symmetry classes of a single bounded-response mechanism; local $\mathrm{U}(1)$ gauge invariance as the residual phase freedom of the projected description.
$\mathrm{SU}(2)$ quaternionic admissibility.
- O23 — $\mathbb{H}$ is the minimal admissible associative non-commutative algebra; $\dim_\mathbb{R} \operatorname{Im}\mathbb{H} = 3$ derives the threshold $\Sigma_c(n_3) = 3$ rather than postulating it.
- O27 — quaternionic rigidity theorem: every admissible morphism $\Phi_{q,\rho}$ factors through $\mathfrak{su}(2)$, proved unconditionally.
- O28 — asymptotic calibration: covariance $\mathcal{C}_c$ has rank 3 with invariant eigenvalue structure $[1 : \tfrac12 : \tfrac12]$.
- O29 — spin-$\tfrac12$ sector identified via the symmetric rank formula; unique solution $d_\rho = 2$ confirmed at $q \in \{61, 101, 151\}$.
- O30 — analytical derivation of the invariant eigenvalue ratio $\lambda_1/\lambda_2 = 2$ from the equatorial fibre constraint.
- Q7 — $H_{\mathrm{eff}} = \mathrm{Sym}^2(V_\rho)$ is the unique irreducible 3D $\mathfrak{su}(2)$-module; spatial and internal $\mathfrak{su}(2)$ structures representation-theoretically locked.
Gauge charges and admissible bundle structure.
- Q6a — full admissible principal bundle $P_{G_\Pi}(M, G_\Pi)$ with $G_\Pi = \mathrm{SU}(3) \times \mathrm{SU}(2) \times \mathrm{U}(1)$; gauge charges as holonomy invariants of the admissible connection.
- Q12 — base–fibre decomposition and horizontal–vertical decoupling lemma: gauge sector $a_4$ and gravitational sector $a_2$ are independent at leading order; gauge group taken as input from Q6a and the O-series.
$\mathrm{SU}(3)$ colour-triplet co-admissibility.
- O31 — metaplectic intertwining forces triplet co-admissibility unconditionally on the colour-adapted Cayley graph; the spectral route to $[\mathrm{H\text{-}color}]$ on the standard graph is closed; $\mathrm{SU}(3)$ identified as the symmetry of co-admissible triplets $\{V_c, V_{\omega c}, V_{\omega^2 c}\}$.
- O32 — $[\mathrm{H\text{-}color}]$ closed at the rank, averaged, and effective-exponent levels; numerical passage at $q \in \{61, 151, 211, 307\}$; finite-$q$ pointwise profile equality proved analytically in O31 v1.5 (single-frequency BI fingerprint), residual $R_{\mathrm{var}}$ reinterpreted as finite-sample auxiliary-draw footprint.
Inputs and outputs
Upstream inputs. The Weil representation $V_\rho \simeq L^2(\mathbb{Z}/q\mathbb{Z})$ as a theorem of the foundational branch; the Born–Infeld bounded-flux constraint; non-injectivity as a structural necessity (ENI); and, from the spectral admissibility sub-programme (Presentation Note 1), the spin-$\tfrac12$ admissible sector, the threshold $\Sigma_c(n_3) = 3$, and $\operatorname{Im}\mathbb{H} \cong \mathfrak{su}(2)$. From the emergent geometry sub-programme (Presentation Note 2), the effective base manifold $\mathbb{R}_\tau \times \mathrm{Heis}_3(\mathbb{R})$ on which the principal bundle is defined.
Outputs. The gauge group $G_\Pi = \mathrm{SU}(3) \times \mathrm{SU}(2) \times \mathrm{U}(1)$; the admissible principal bundle $P_{G_\Pi}(M, G_\Pi)$; charge quantisation $q_{\mathrm{eff}} = w \cdot e$ with absence of magnetic monopoles on the canonical model; $d_\rho = 2$ and $\mathfrak{su}(2)$ closure; $\mathrm{SU}(3)$ unconditional on the standard graph via $[\mathrm{H\text{-}color}]_{\mathrm{pointwise}}$ (O31 v1.5, single-frequency BI fingerprint); projective chirality — consumed by Q12, Q13, Q14 and the gauge–gravity stratification sub-programme.
Status
The gauge group identification is closed at all three levels ($\mathrm{U}(1)$, $\mathrm{SU}(2)$, $\mathrm{SU}(3)$): $\mathrm{U}(1)$ and $\mathrm{SU}(2)$ analytically via the Hopf phase fibre and the O27 rigidity theorem; $\mathrm{SU}(3)$ unconditionally on the colour-adapted graph (O31) and at all four analytical levels (rank, averaged, effective-exponent, and pointwise) on the standard graph (O31 v1.5–O32), the last via Proposition 4.23 of O31 (single-frequency BI fingerprint structure). Two items remain open: the extension of the topological exclusion of magnetic monopoles ($\pi_2(\mathcal{C}_{\mathrm{eff}}) = 0$) beyond the canonical model; and the derivation of the specific $V - A$ structure of the weak interaction current from admissibility data. This note does not derive Yang–Mills dynamics — that belongs to the gauge–gravity spectral stratification sub-programme (Presentation Note 8).