Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Trion ladder diagrams   We first derive a new ``commutation technique'' for an exciton interacting
with electrons, inspired from the one we recently developed for excitons
interacting with excitons. These techniques allow to take \emph{exactly} into
account the possible exchanges between carriers. We use it to get the
$\mathrm{X}^-$ trion creation operator in terms of exciton and free-electron
creation operators. In a last part we generate the ladder diagrams associated
to these trions. Although similar to the exciton ladder diagrams, with the hole
replaced by an exciton, they are actually much more tricky : (i) Due to the
composite nature of the exciton, one cannot identify an exciton-electron
potential similar to the Coulomb potential between electron and hole ; (ii) the
spins are unimportant for excitons while they are crucial for trions, singlet
and triplet states having different energies.

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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
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The categories of this paper are: atom-ph