Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: U(1) Axial Symmetry and Correlation Functions in the High Temperature
  Phase of QCD   Simple group-theoretical arguments are used to demonstrated that in the high
temperature (chirally restored) phase of QCD with N massless flavours, all
n-point correlation functions of quark bilinears are invariant under U(1) axial
transformations provided n < N. In particular this implies that the two-point
correlation function in the eta' channel is identical to that in the pion
channel for N > 2. Unlike previous work, this result does not depend on the
topological properties of QCD and can be formulated without explicit reference
to functional integrals.

23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
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The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph