Sensitivity of Tunneling-Rotational Transitions in Ethylene Glycol to
  Variation of Electron-to-Proton Mass Ratio
  Ethylene glycol in its ground conformation has tunneling transition with the
frequency about 7 GHz. This leads to a rather complicated tunneling-rotational
spectrum. Because tunneling and rotational energies have different dependence
on the electron-to-proton mass ratio $\mu$, this spectrum is highly sensitive
to the possible $\mu$ variation. We used simple 14 parameter effective
Hamiltonian to calculate dimensionless sensitivity coefficients $Q_\mu$ of the
tunneling-rotational transitions and found that they lie in the range from
$-17$ to $+18$. Ethylene glycol has been detected in the interstellar medium.
All this makes it one of the most sensitive probes of $\mu$ variation at the
large space and time scales.
