Indications of Electron-to-Proton Mass Ratio Variations in the Galaxy. III. 0.6 mm Methanol Lines Toward Sgr B2(N) and Orion-KL

In this paper, we show that methanol (CH 3 OH), torsional-rotational transitions, which have increased sensitivity to small variations of the electron-to-proton mass ratio μ, are shifted relative to less sensitive transitions in the spectrum of the Sgr B2(N) molecular cloud located at the Galactic center. At the same time, an identical set of methanol lines in the spectrum of the Orion-KL molecular cloud, located far from the center, shows no shifts. Interpreting this behavior of molecular frequencies in terms of Δ μ /μ = (μ _obs - μ _lab)/μ _lab leads to the following weighted mean values: Δ μ /μ \, = \,( - 3.4\, ± \,0.4) × 10^ - 7 for Sgr B2 and Δ μ /μ \, = \,( - 1.1 ± 0.8) × 10 –7 for Orion-KL (indicated are the total ± 1σ errors of the weighted means Δ μ /μ including both statistical and systematic uncertainties). A possible correlation between Δ μ /μ values measured in various molecular clouds of the Galactic disk and the distribution of dark matter along the Galactic radius is discussed, which may suggest a hypothetical modulation of the Higgs scalar field by dark matter, resulting in a change of μ .