Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature and Density Effects on the Nucleon Mass Splitting   The finite temperature and finite density dependence of the neutron-proton
mass difference is analysed in a purely hadronic framework where the
$\rho-\omega $ mixing is crucial for this isospin symmetry breakdown. The
problem is handled within Thermo Field Dynamics. The present results,
consistent with partial chiral and charge symmetry restoration, improve the
experimental data fit for the energy difference between mirror nuclei.

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The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg