Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac
  fermions in the 2D and 3D topological insulator Bi2Se3
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
19
The categories of this paper are: eess
18
The categories of this paper are: econ