Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Differential and partial cross sections of elastic and inelastic
  positronium-helium-atom scattering   Scattering of positronium (Ps) by helium atom has been investigated in a
three-Ps-state coupled-channel model including Ps(1s,2s,2p) states using a
recently proposed time-reversal-symmetric regularized electron-exchange model
potential. Specifically, we report results of differential cross sections for
elastic scattering and target-elastic Ps excitations. We also present results
for total and different partial cross sections and compare them with experiment
and other calculations.

16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas