Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical clocks based on molecular vibrations as probes of variation of
  the proton-to-electron mass ratio   Some new physics models of quantum gravity or dark matter predict drifts or
oscillations of the fundamental constants. A relatively simple model relates
molecular vibrations to the proton-to-electron mass ratio $\mu$. Many
vibrational transitions are at optical frequencies with prospects for use as
highly accurate optical clocks. We give a brief summary of new physics models
that lead to changes in $\mu$ and the current limits on drifts and oscillation
amplitudes. After an overview of laboratory procedures, we give examples of
molecules with experiments currently in development or underway. These
experiments' projected systematic and statistical uncertainties make them
leading candidates in next-generation searches for time-variation of $\mu$.

23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph