Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single eta production in heavy quarkonia: breakdown of multipole
  expansion   The $\eta$ production in the $(n,n')$ bottomonium transitions $\Upsilon (n)
\to \Upsilon (n') \eta, $ is studied in the method used before for dipion heavy
quarkonia transitions. The widths $\Gamma_\eta(n,n')$ are calculated without
fitting parameters for $n=2,3,4,5, n'=1$. Resulting $\Gamma_\eta(4,1)$ is found
to be large in agreement with recent data. Multipole expansion method is shown
to be inadequate for large size systems considered.

17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph