Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A search for an unexpected asymmetry in the production of $e^+ \mu^-$
  and $e^- \mu^+$ pairs in proton-proton collisions recorded by the ATLAS
  detector at $\sqrt s = 13$ TeV   This search, a type not previously performed at ATLAS, uses a comparison of
the production cross sections for $e^+ \mu^-$ and $e^- \mu^+$ pairs to
constrain physics processes beyond the Standard Model. It uses $139
\text{fb}^{-1}$ of proton$-$proton collision data recorded at $\sqrt{s} = 13$
TeV at the LHC. Targeting sources of new physics which prefer final states
containing $e^{+}\mu^{-}$ to $e^{-}\mu^{+}$, the search contains two broad
signal regions which are used to provide model-independent constraints on the
ratio of cross sections at the 2% level. The search also has two special
selections targeting supersymmetric models and leptoquark signatures.
Observations using one of these selections are able to exclude, at 95%
confidence level, singly produced smuons with masses up to 640 GeV in a model
in which the only other light sparticle is a neutralino when the
$R$-parity-violating coupling $\lambda'_{231}$ is close to unity. Observations
using the other selection exclude scalar leptoquarks with masses below 1880 GeV
when $g_{\text{1R}}^{eu}=g_{\text{1R}}^{\mu c}=1$, at 95% confidence level. The
limit on the coupling reduces to $g_{\text{1R}}^{eu}=g_{\text{1R}}^{\mu
c}=0.46$ for a mass of 1420 GeV.

20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ