Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perspective: Tipping the scales - search for drifting constants from
  molecular spectra   Transitions in atoms and molecules provide an ideal test ground for
constraining or detecting a possible variation of the fundamental constants of
nature. In this Perspective, we review molecular species that are of specific
interest in the search for a drifting proton-to-electron mass ratio $\mu$. In
particular, we outline the procedures that are used to calculate the
sensitivity coefficients for transitions in these molecules and discuss current
searches. These methods have led to a rate of change in $\mu$ bounded to $6
\times 10^{-14}$/yr from a laboratory experiment performed in the present
epoch. On a cosmological time scale the variation is limited to
$|\Delta\mu/\mu| < 10^{-5}$ for look-back times of 10-12 billion years and to
$|\Delta\mu/\mu| < 10^{-7}$ for look-back times of 7 billion years. The last
result, obtained from high-redshift observation of methanol, translates into
$\dot{\mu}/\mu = (1.4 \pm 1.4) \times 10^{-17}$/yr if a linear rate of change
is assumed.

17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc