Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nucleon - Nucleon Interactions at Short Distances   Despite the progress made in understanding the NN interactions at long
distances based on effective field theories, the understanding of the dynamics
of short range NN interactions remains as elusive as ever. One of the most
fascinating properties of short range interaction is its repulsive nature which
is responsible for the stability of strongly interacting matter. The relevant
distances, $\le 0.5$ fm, in this case are such that one expects the onset of
quark-gluon degrees of freedom with interaction being dominated by QCD
dynamics. We review the current status of the understanding of the QCD dynamics
of NN interactions at short distances, highlight outstanding questions and
outline the theoretical foundation of QCD description of hard NN processes. We
present examples of how the study of the hard elastic NN interaction can reveal
the symmetry structure of valence quark component of the nucleon wave function
and how the onset of pQCD regime is correlated with the onset of color
transparency phenomena in hard $pp$ scattering in the nuclear medium. The
discussions show how the new experimental facilities can help to advance the
knowledge about the QCD nature of nuclear forces at short distances.

34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess