Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge-exchange quasi-elastic process $nd\to p(nn)$ under $0^\circ$ in
  the frame of elastic $np\to np$ scattering to $180^\circ$   It is considered the problem of spin physics related with the difference of
representation of the elastic interaction between the neutron and proton. In
the first case the charge-exchange reaction $np\to pn$ under the angle $\theta$
is supposed, in the second --- the simple elastic scattering of $np\to np$,
when the neutron is going in opposite direction $\pi-\theta$. The transition
from one representation to another is provided by the Majorana operator. In the
framework of impulse approximation it is twice calculated the quasi-elastic
charge-exchange reaction of a neutron on a deuteron. In the frame of $nd\to
p(nn)$ scattering of proton to the angle $\theta$ it gives the well-known Dean
formula. Using other representation $nd\to (nn)p$ as a neutron elastic
scattering under the angle $\pi-\theta$ (together with neutron-spectator in
$nn$-pair) the alternative formula is presented.

21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con