Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The Fermionic Particle Density of Flat 1+1 Dimensional Spacetime seen by
  an Arbitrarily Moving Observer
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con