Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multinucleon Mechanisms in ($\gamma$,N) and ($\gamma$,NN) Reactions   The similarities in the experimental indications for multinucleon mechanisms
in $(\gamma,p)$ and $(e,e'p)$ processes are pointed out. For both types of
reactions, the substantial role of two-nucleon emission processes for
transitions to high excitation energies in the residual nucleus is stressed. A
microscopic model for the calculation of the two-body knockout contributions to
the inclusive $(\gamma,N)$ reaction is presented. It is based on an
unfactorized formalism for the calculation of electromagnetically induced
two-nucleon emission cross sections. The model is shown to yield a reasonable
description of the overall behaviour of the $^{12}$C$(\gamma,p)$ and
$^{12}$C$(\gamma,n)$ data at high excitation energies in the residual nucleus.
In the calculations effects from non-resonant and resonant pion exchange
currents are included. Photoabsorption on these currents are predicted to
produce the major contributions to the exclusive $^{16}$O$(\gamma,n_0)^{15}$O
process at photonenergies above the pion threshold. Double differential cross
sections for photon induced $pp$ and $pn$ emission from $^{16}$O are calculated
and compared with the data.

15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th