Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalies and discrete chiral symmetries   The quantum anomaly that breaks the U(1) axial symmetry of massless
multi-flavored QCD leaves behind a discrete flavor-singlet chiral invariance.
With massive quarks, this residual symmetry has a close connection with the
strong CP-violating parameter theta. One result is that if the lightest quarks
are degenerate, then a first order transition will occur when theta passes
through pi. The resulting framework helps clarify when the rooting prescription
for extrapolating in the number of flavors is valid.

3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess