Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutrino flavor oscillations in background matter   We study the evolution of two mixed Dirac neutrinos in an external
axial-vector field. The dynamics of this system is described in the framework
of relativistic wave equations approach on the basis of the known solutions of
the Dirac equation in an external field with a given initial condition. The
general solution of the initial condition problem, exactly accounting for the
external field, is obtained. Then we consider special form of the external
field which corresponds to the standard model neutrino interactions with the
background matter. In this limit we derive the transition probability and
compare it with the previously known results.

35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol