Abstract
We present a new formula for the cosmological constant:
where is the fine structure constant, the electron mass, the Planck mass, and the Planck length. The formula predicts m⁻², within 1.9% of the Planck 2018 observed value — at the edge of the current 1σ observational uncertainty. The exponent structure is different from that of all previously known formulas, including the Beck–Nottale–Boehmer–Harko result, which has 25% error. The vacuum energy density implied by the formula admits a suggestive algebraic decomposition: . We identify each factor with a physical scale: has the form of a one-loop electron vacuum energy; matches the order of the first genuinely nonlinear QED vacuum effect (light-by-light scattering); and is a gravitational suppression factor corresponding to a single graviton vertex. The implied dark energy scale is 2.25 meV, matching the observed ~2.3 meV. Unlike Dirac-type large-number coincidences, the formula involves only true constants (, , , , ). Four additional predictions follow: a strictly constant equation of state (a sharp test of the present DESI 2024 BAO hint of dark energy evolution, to be resolved by DESI Y3/Y5), no time-variation of (consistent with ESPRESSO), a selection rule that suppresses heavier-lepton contributions, and sub-percent testability of the value itself by DESI Y3 and Euclid within 2–3 years.