Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photoassociation of ultracold molecules near a Feshbach resonance as a
  probe of the electron-proton mass ratio variation   We show that the photoassociation (PA) rate of ultracold diatomic molecules
in the vicinity of a Feshbach resonance could be used to probe variations of
the electron-to-proton mass ratio $\beta = m_e/m_p$, a quantity related to
other fundamental constants via the $\Lambda_{\mathrm{QCD}}$ scale. The PA rate
exhibits two features near a Feshbach resonance, a minimum and a maximum, which
are very sensitive to the details of the interactions and the exact mass of the
system. The effect and detection threshold are illustrated in the formation
rates of ultracold Li$_2$ and LiNa molecules by performing coupled-channel
calculations in an external magnetic field. We find that the PA rate is
particularly sensitive near narrow Feshbach resonances in heavy molecules,
where it might be possible to detect relative variability of $\beta$ on the
order of $10^{-15}-10^{-16}$. We also use a two-channel model to derive a
proportionality relation between the variation of the PA rate and $\beta$
applicable to diatomic molecules.

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The categories of this paper are: hep-ph
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph