Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Next-to-next-to-leading-order QCD corrections to $e^+e^-\to
  J/\psi+\eta_c$ at $B$ factories   Within the nonrelativistic QCD (NRQCD) factorization framework, we compute
the long-awaited ${\mathcal O}(\alpha_s^2)$ correction for the exclusive double
charmonium production process at $B$ factories, i.e., $e^+e^-\to J/\psi+\eta_c$
at $\sqrt{s}=10.58$ GeV. For the first time, we confirm that NRQCD
factorization does hold at next-to-next-to-leading-order (NNLO) for exclusive
double charmonium production. It is found that including the NNLO QCD
correction greatly reduces the renormalization scale dependence, and also
implies the reasonable perturbative convergence behavior for this process. Our
state-of-the-art prediction is consistent with the BaBar measurement.

5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg