Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Central exclusive production of scalar and pseudoscalar charmonia in the
  light-front $k_T$-factorization approach   We study exclusive production of scalar $\chi_{c0}\equiv \chi_c(0^{++})$ and
pseudoscalar $\eta_c$ charmonia states in proton-proton collisions at the LHC
energies. The amplitudes for $gg \to \chi_{c0}$ as well as for $gg \to \eta_c$
mechanisms are derived in the $k_{T}$-factorization approach. The $p p \to p p
\eta_c$ reaction is discussed for the first time. We have calculated rapidity,
transverse momentum distributions as well as such correlation observables as
the distribution in relative azimuthal angle and $(t_1,t_2)$ distributions. The
latter two observables are very different for $\chi_{c0}$ and $\eta_c$ cases.
In contrast to the inclusive production of these mesons considered very
recently in the literature, in the exclusive case the cross section for
$\eta_c$ is much lower than that for $\chi_{c0}$ which is due to a special
interplay of the corresponding vertices and off-diagonal UGDFs used to
calculate the cross sections. We present the numerical results for the key
observables in the framework of potential models for the light-front quarkonia
wave functions. We also discuss how different are the absorptive corrections
for both considered cases.

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The categories of this paper are: math
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
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The categories of this paper are: astro-ph
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci