Within the Floriano Unified Theory (TUF), we derive the observed cosmological constant Λₒbs from first principles using zero free parameters. The derivation has two parts: (1) exact cancellation — the electron, as the unique zero mode of the hyperspace Dirac operator D_Ξ, forces the vacuum curvature R (Ξ) |ᵥac = 0 via the Atiyah–Singer index theorem, cancelling the vacuum energy identically; (2) residual Λ from spectral resonance — three resonances between PSL (2, p) representation theory and TUF quantum numbers determine the moduli-space volume Vol (Ξ) /ℓP⁴ = 7×19×409 = 54397, yielding ΛTUF = 1. 108×10⁻⁵² m⁻², agreeing with Λₒbs = 1. 106×10⁻⁵² m⁻² to 0. 20% with zero free parameters. Open problems explicitly documented: the p=7 and p=19 PSL (2, p) resonances are algebraically sharp for p=409 but remain conjectural for p=7 and p=19, pending rigorous derivation from representation theory. This paper is part of the TUF series: - Paper 0 (Ontological Foundation): https: //doi. org/10. 5281/zenodo. 19024705- Paper 1 (Fermion masses): https: //doi. org/10. 5281/zenodo. 18988060- Paper 2 (Three generations): https: //doi. org/10. 5281/zenodo. 18991190- Paper 3 (Dark matter): https: //doi. org/10. 5281/zenodo. 18991306
Fabián Flor (Sat,) studied this question.