Differential measurement of m_e/m_p: 3 mm methanol lines toward Sagittarius B2(N) and (M) molecular clouds

Differential measurement of the fundamental physical constant mu = m_e/m_p (the electron-to-proton mass ratio) toward two sources located near the Galactic center - the Sagittarius (Sgr) B2(N) and (M) molecular clouds - show a lower mu compared to its terrestrial value. Based on methanol (CH3OH) emission lines from the frequency range 80-112 GHz (IRAM 30-m telescope archival data), the calculated difference (Delta mu)/mu = (mu_obs - mu_lab)/mu_lab is equal to (-3.0 +/- 0.6)*10^(-7) (1 sigma C.L.) in the whole cloud SgrB2. The revealed 5 sigma signal in mu-variations agrees within the margin of error with the recently obtained result based on methanol emission lines from the higher frequency range 542-543 GHz (Herschel space telescope archival data) for SgrB2(N): (Delta mu)/mu = (-4.2 +/- 0.7)*10^(-7).