Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The role of $U(1)_A$ symmetry breaking in the QCD corrections to the
  pion mass difference   The charged and neutral pion mass difference can be attributed to both the
QED and QCD contributions. The current quark mass difference ($\Delta m$) is
the source of the QCD contribution. Here, in a two flavour non-local NJL model,
we try to estimate the QCD contribution. Interestingly, we find that the
strength of the $U(1)_A$ symmetry breaking parameter $c$ plays a crucial role
for obtaining the pion mass difference while intertwined with the current quark
mass difference. To obtain the QCD contribution for the pion mass difference we
can scan the parameter space in $\{\Delta m,\; c\}$ and by comparing this with
the existing results this parameter space is constrained. Further, using a
fitted value of $c$ we can determine the allowed range for the current quark
mass difference in the model.

18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin