Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Equilibrium properties of self-interacting neutrinos in the
  quasi-particle approach   In this work a neutrino gas in equilibrium is studied both at T=0 and at
finite temperature. Neutrinos are treated as massive Dirac quasi-particles with
two generations. We include self-interactions among the neutrinos via neutral
currents, as well as the interaction with a background of matter. To obtain the
equilibrium properties we use Wigner function techniques. To account for
corrections beyond the Hartree approximation, we also introduce correlation
functions. We prove that, under the quasi-particle approximation, these
correlation functions can be expressed as products of Wigner functions. We
analyze the main properties of the neutrino eigenmodes in the medium, such as
effective masses and mixing angle. We show that the formulae describing these
quantities will differ with respect to the case with no self-interactions.

3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg