Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Doping evolution of charge and spin excitations in two-leg Hubbard
  ladders: comparing DMRG and RPA+FLEX results
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph