Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Positronium atom scattering by H_2 in a coupled-channel framework   The scattering of ortho positronium (Ps) by H$_2$ has been investigated using
a three-Ps-state [Ps(1s,2s,2p)H$_2($X $^1\Sigma_g^+$)] coupled-channel model
and using Born approximation for higher excitations and ionization of Ps and B
$^1\Sigma_u^+$ and b $^3\Sigma_u^+$ excitations of H$_2$. We employ a recently
proposed time-reversal-symmetric nonlocal electron-exchange model potential. We
present a calculational scheme for solving the body-frame fixed-nuclei
coupled-channel scattering equations for Ps-H$_2$, which simplifies the
numerical solution technique considerably. Ps ionization is found to have the
leading contribution to target-elastic and all target-inelastic processes. The
total cross sections at low and medium energies are in good agreement with
experiment.

10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org