Constraints on the variation of the QCD interaction scale ΛQCD

A bstract Laboratory and astrophysical tests of “constant variation” have so far concentrated on the dimensionless fine-structure constant α and on the electron or quark mass ratios X e , q = m e , q /Λ QCD , treating the QCD scale Λ QCD as unchangeable. Certain beyond Standard Model frameworks, most notably those with a dark matter or dark energy scalar field ϕ coupling with the gluon field, would make Λ QCD itself time dependent while leaving α and the electron mass untouched. Under the minimal assumption that this gluonic channel is the sole ϕ interaction, we recast state-of-the-art atomic clock comparisons into Λ̇QCD/ΛQCD Λ ̇ QCD / Λ QCD = (3.2 ± 3.5) × 10 −17 yr −1 limits, translate the isotope yields of the 1.8-Gyr-old Oklo natural reactor into a complementary geophysical limit of | δ Λ QCD /Λ QCD | < 2 × 10 −9 over that time span, corresponding to the linear drift limit |Λ̇QCD/ΛQCD| Λ ̇ QCD / Λ QCD < 1 × 10 −18 yr −1 , and show that the proposed 8 . 4 eV 229 Th nuclear clock would amplify a putative Λ QCD drift by four orders of magnitude compared with present atomic clocks. We also obtain constraints from quasar absorption spectra and Big Bang Nucleosynthesis data.