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 $$ {\dot{\Lambda}}_{\textrm{QCD}}/{\Lambda}_{\textrm{QCD}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mover> <mml:mi>Λ</mml:mi> <mml:mo>̇</mml:mo> </mml:mover> <mml:mi>QCD</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>Λ</mml:mi> <mml:mi>QCD</mml:mi> </mml:msub> </mml:math> = (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 | &lt; 2 × 10 −9 over that time span, corresponding to the linear drift limit $$ \left|{\dot{\Lambda}}_{\textrm{QCD}}/{\Lambda}_{\textrm{QCD}}\right| $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:mrow> <mml:msub> <mml:mover> <mml:mi>Λ</mml:mi> <mml:mo>̇</mml:mo> </mml:mover> <mml:mi>QCD</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>Λ</mml:mi> <mml:mi>QCD</mml:mi> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> &lt; 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.