A Geometric Origin for the Cosmological Constant from CPT-Symmetric Branes: Framework, Flux Stabilization, and Topological Quantization of 𝜌 Λ

Abstract We present the Dual-Brane Quantum Tunneling Model (DBQTM), a geometrically motivated framework for the cosmological constant based on a CPT-symmetric two-brane configuration in a Randall–Sundrum background with Goldberger–Wise stabilization. The observed vacuum energy arises from inter-brane mixing suppression ρΛ=k4exp⁡(−ηgeo kd), with k=0.0869 MPl, ηgeo=0.720, and kd≈375. The 122‑order hierarchy between the natural and observed vacuum energy scales is recast as a moderately large geometric product ηgeokd≈270. We show that a Klebanov–Strassler embedding determines the brane separation through quantized 3‑form fluxes, kd=2πKgsM, with flux integers K=203, M=17, and string coupling gs=1/5, reproducing the observed value of ρΛ within 2%. The cosmological constant becomes a topological invariant fixed by discrete flux data. We derive the Binetruy–Deffayet–Langlois junction conditions, establish a no‑go theorem for observable deviations from w=−1, and analyze the holographic interpretation of the suppression mechanism. The DBQTM provides a unified geometric origin for the cosmological constant without fine‑tuning.