Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Universality Class in three dimensions: the Antiferromagnetic $RP^2$
  model   We present the results of a Monte Carlo simulation of the $RP^2$ model in
three dimensions with negative coupling. We observe a second order phase
transition between the disordered phase and an antiferromagnetic, unfrustrated,
ordered one. We measure, with a Finite Size Scaling analysis, the thermal
exponent, obtaining $\nu=0.784(8)$. We have found two magnetic-type relevant
operators whose related $\eta$ exponents are $0.038(2)$ and $1.338(8)$
respectively.

5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th