Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Progress in the Development of Global Medium-Energy Nucleon-Nucleus
  Optical Model Potentials   Two existing global medium-energy nucleon-nucleus phenomenological optical
model potentials are described and compared with experiment and with each
other. The first of these employs a Dirac approach (second-order reduction)
that is global in projectile energy and projectile isospin and applies to the
target nucleus 208-Pb. Here the standard S-V (isoscalar-scalar,
isoscalar-vector) model has been extended to include the corresponding
isovector components by introduction of a relativistic Lane model. The second
of these employs a relativistic equivalent to the Schroedinger equation and is
global in projectile energy, projectile isospin, and target (Z,A). Here,
particular attention is given to predictions for the integrated scattering
observables - neutron total cross sections and proton total reaction cross
sections - and their sensitivity to the absorptive parts of the potential.
Finally, current work is described and the influence of the nuclear bound state
problem (treated in relativistic mean field theory) on the Dirac scattering
problem is mentioned.

37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex