Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Study of pseudogap and superconducting quasiparticle dynamics in
  $\rm{Bi_2Sr_2CaCu_2O_{8+\delta}}$ by time-resolved optical reflectivity
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph