Yang–Mills Dynamics from Projective Spectral Entropy: Vertical Heat-Kernel Variation on the Admissible Fibre

The companion Gravity paper showed that the horizontal variation of the projective spectral entropy functional S_ = 12' Ag with respect to the base metric produces the Einstein tensor as the infrared-dominant response, through the Seeley–DeWitt coefficient a₂. The present paper carries out the complementary vertical variation. Extending Ag to a Laplace-type operator A₆, ₀ = - (^A) ² + E on the associated vector bundle of the admissible principal fibre, with the connection and the fibre representation held fixed, we compute the local logarithmic part of the Seeley–DeWitt coefficient a₄ and isolate its gauge component, the Yang–Mills density 112\, tr_ (F_F^). Varying S_, A with respect to the admissible connection at fixed base metric then yields the source-free Yang–Mills equations D_ F^a = 0. This local kinetic Yang–Mills sector, and its variation, are the robust result of the paper. The coefficient of the induced logarithm depends on the fibre representation content through the Dynkin index I_ and is therefore not universal. The physical gauge coupling gₘ₌, like Newton's constant, remains a renormalized matching datum, of which only the logarithmic running is computed here; a single logarithmic divergence does not by itself establish asymptotic freedom, which depends on the full projected field content and is not claimed. What is structural, within the proper-time scheme used here, is the difference in ultraviolet divergence degree between the two sectors — quadratic at a₂ for gravity, logarithmic at a₄ for gauge — and not any predicted numerical hierarchy of the physical couplings; the contrast is not scheme-independent, the zeta-regularized determinant carrying no power divergences. The structure group G_ is a supplied input: it is any compact Lie group, and every result below is stated for that class. The gauge-structure sub-programme does not identify it, and in particular does not establish the composite G_ = SU (3) (2) (1) or its colour factor. Interpretation. The result suggests that, within this framework, the natural organisational space for unification may be spectral and variational rather than purely group-theoretic: gravity and gauge dynamics are separated by geometric direction (horizontal versus vertical) and by heat-kernel order. This reading is offered as an interpretive outlook, not as a theorem.