A QCD scale selection for the dark-energy density

DescriptionA light-quark QCD scale at 146–148 MeV yields a pion contribution equal to 0.93 ± 0.14 of the observed dark-energy density and defines a direct lattice falsification test. Abstract We compute a QCD vacuum contribution that survives today with the form of a cosmological constant within a trace-free/source-complete gravitational reading. Using published pion-scattering data together with an independent lattice-QCD determination of the light-quark thermal response, we obtain a light-channel contribution of (2.33 ± 0.34) × 10^-47 GeV^4, i.e. 0.93 ± 0.14 of the observed dark-energy density. The result is not fitted to the cosmological target. The calculation selects a narrow 146–148 MeV light-quark band, quantitatively disfavors nearby generic-crossover and strange-like alternatives under the same map, and is supported by a separate distance-based check landing in the same range. The decisive falsifier is a direct lattice computation of the renormalized light/strange/gluonic susceptibility matrix: the dominant infrared mode must peak in the 146–148 MeV band and be light-quark dominated. This record contains the main article, Extended Data, Supplementary Information, and Source Data.