Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NN($^1S_0$) pairs in $^3$He and in p$^3$He backward elastic scattering   It is shown that the shoulder observed in the cross section of $p^3He$
backward elastic scattering at proton beam energies of 0.4 -- 0.7 GeV can be
explained by the mechanism of virtual $\pi$-meson production with a dominant
contribution from the subprocesses $pd^*\to ^3$He$ \pi^0$ and $p(pp)\to^3$He$
\pi^+$, where $d^*$ denotes the singlet deuteron and the $pp$ pair is in the
$^1S_0$ state. At high energies, 1-3 GeV, the mechanism of $np$-pair transfer
dominates and probes high-momentum $NN(^1S_0$) correlations in $^3$He.

4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int