Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of phonon-assisted luminescence in solids: application to
  hexagonal boron nitride   In this manuscript we study luminescence of hexagonal boron nitride (hBN) by
means of non-equilibrium Green's functions plus time-dependent perturbation
theory. We derive a formula for light emission in solids in the limit of a weak
excitation that includes perturbatively the contribution of electron-phonon
coupling at the first order. This formula is applied to study luminescence in
bulk hBN. This material has attracted interest due to its strong luminescence
in the ultraviolet [Watanabe et al., Nature Mat. 3, 404(2004)]. The origin of
this luminescence has been widely discussed, but only recently has a clear
signature of phonon mediated light emission emerged in the experiments
[Cassabois et al., Nature Phot. 10, 262(2016)]. By means of our new theoretical
approach we provide a clear and full explanation of light emission in hBN.

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The categories of this paper are: funct-an
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess