Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interpretation of structure in the di-$J/\psi$ spectrum   Structure in the di-$J/\psi$ mass spectrum observed by the LHCb experiment
around 6.9 and 7.2 GeV is interpreted in terms of $J^{PC}=0^{++}$ and $2^{++}$
resonances between a $cc$ diquark and a $\bar c \bar c$ antidiquark, using a
recently confirmed string-junction picture to calculate tetraquark masses. The
main peak around 6.9 GeV is likely dominated by the $0^{++}(2S)$ state, a
radial excitation of the $cc$-$\bar c \bar c$ tetraquark, which we predict at
$6.871\pm 0.025$ GeV. The dip around 6.75 GeV is ascribed to the opening of the
\Swave\ di-$\chi_{c0}$ channel, while the dip around 7.2 GeV could be
correlated with the opening of the di-$\eta_c(2S)$ or $\Xi_{cc} \bar \Xi_{cc}$
channel. The low-mass part of the di-$J/\psi$ structure appears to require a
broad resonance consistent with a predicted $2^{++}(1S)$ state with invariant
mass around $M_{\rm inv} = 6400$ MeV. Implications for $bb \bar b \bar b$
tetraquarks are discussed.

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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: mtrl-th