Key points are not available for this paper at this time.
We describe a new technique to measure variations in the fundamental parameters \ and y \ mₑ/mₚ, using the sum of the frequencies of cm-wave OH ``main'' lines. The technique is \ three orders of magnitude more sensitive than that of Chengalur the detection of the main 6cm OH line in any of these systems would thus be sufficient to simultaneously constrain changes in \ and y between the absorption redshift and today.
Kanekar et al. (Wed,) studied this question.