Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exclusive J/\psi Productions at e^+ e^- Colliders   Exclusive quarkonium pair production in electron-positron collisions is
studied in non-relativistic QCD. The obtained cross section for J/\psi + \eta_c
production in the leading order is confronted against the recent measurements
by the Belle Collaboration at KEKB. It is shown that a large renormalization
K-factor is necessary to explain the experimental data. We point out that the
J^{PC}=0^{-+} nature of the hadronic systems that are assigned to be \eta_c
should be tested by the triple angular distributions in terms of the scattering
angle, and, polar and azimuthal angles of J/\psi into leptons. We further study
J/\psi + J/\psi and \Upsilon + \Upsilon productions at LEP energies. Although
the axial-vector couplings of the Z-boson to charm and bottom quarks allow
production of such pairs when one of them is polarised transversally and the
other longitudinally, we find that the integrated luminosity at Z pole
accumulated by LEP is not large enough to observe the exclusive pair production
of quarkonium.

30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con