Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Origin of the excitonic recombinations in hexagonal boron nitride by
  spatially resolved cathodoluminescence spectroscopy
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol