A Fixed-Point Derivation of the Observed Vacuum Energy from Moduli Stabilization in Type IIB String Theory

The cosmological constant problem—why the observed vacuum energy density is extremely small yet positive—remains unresolved within conventional string theory. This work presents a constructive resolution within the QuEST framework via symbolic causal geometry, giving a self-contained derivation of the observed vacuum energy scale inside a Type IIB compactification background. Building on the Kachru–Kallosh–Linde–Trivedi (KKLT) setup, the analysis embeds three independently derived QuEST structural mechanisms into the effective theory: fixed-point stabilization, a bulk informational constraint, and a universal symbolic suppression law. Imposing these mechanisms reshapes the stabilized scalar potential so that, after canonical normalization, the vacuum energy acquires a double-exponential suppression without parameter fitting. The uplift required to obtain a small positive vacuum energy is shown to emerge structurally from flux quantization and warped throat geometry, rather than from external tuning. The resulting construction predicts a modulus mass compatible with radiative stability and yields an expansion rate consistent with current cosmological observations. Although formulated within string-theoretic language, the decisive selection principles originate from QuEST’s symbolic causal geometry, providing a non-anthropic mechanism for the small positive cosmological constant without ad hoc fine-tuning.