Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Brightening of spin- and momentum-dark excitons in transition metal
  dichalcogenides   Monolayer transition metal dichalcogenides (TMDs) have been in focus of
current research, among others due to their remarkable exciton landscape
consisting of bright and dark excitonic states. Although dark excitons are not
directly visible in optical spectra, they have a large impact on exciton
dynamics and hence their understanding is crucial for potential TMD-based
applications. Here, we study brightening mechanisms of dark excitons via
interaction with phonons and in-plane magnetic fields. We show clear signatures
of momentum- and spin-dark excitons in WS$_2$, WSe$_2$ and MoS$_2$, while the
photoluminescence of MoSe$_2$ is only determined by the bright exciton. In
particular, we reveal the mechanism behind the brightening of states that are
both spin- \textit{and} momentum-dark in MoS$_2$. Our results are in good
agreement with recent experiments and contribute to a better microscopic
understanding of the exciton landscape in TMDs.

20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an