Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Arf-Brown TQFT of Pin$^-$ Surfaces   The Arf-Brown invariant $\mathit{AB}(\Sigma)$ is an 8th root of unity
associated to a surface $\Sigma$ equipped with a pin$^-$ structure. In this
note we investigate a certain fully extended, invertible, topological quantum
field theory (TQFT) whose partition function is the Arf-Brown invariant. Our
motivation comes from the recent work of Freed-Hopkins on the classification of
topological phases, of which the Arf-Brown TQFT provides a nice example of the
general theory; physically, it can be thought of as the low energy effective
theory of the Majorana chain, or as the anomaly theory of a free fermion in 1
dimension.

35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ