Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for charged lepton-flavour violation in top-quark decays at the
  LHC with the ATLAS detector   A direct search for charged lepton-flavour violation in top-quark decays is
presented. The data analysed correspond to $79.8\ \text{fb}^{-1}$ of
proton--proton collisions at a centre-of-mass energy of $\sqrt{s}=13\
\text{TeV}$ recorded by the ATLAS experiment at the LHC. The process studied is
the production of top-quark pairs, where one top quark decays into a pair of
opposite-sign different-flavour charged leptons and an up-type quark, while the
other decays semileptonically according to the Standard Model. The signature of
the signal is thus characterised by the presence of three charged leptons, a
light jet and a $b$-jet. A multivariate discriminant is deployed and its
distribution used as input to extract the signal strength. In the absence of a
signal, an upper limit on the branching ratio of ${\cal B}(t \to \ell \ell' q)
< 1.86 \times 10^{-5}$ is set at the 95\% confidence level.

15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph