Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synchronization vs. decoherence of neutrino oscillations at intermediate
  densities   We study collective oscillations of a two-flavor neutrino system with
arbitrary but fixed density. In the vacuum limit, modes with different energies
quickly de-phase (kinematical decoherence), whereas in the limit of infinite
density they lock to each other (synchronization). For intermediate densities,
we find different classes of solutions. There is always a phase transition in
the sense of partial synchronization occurring only above a density threshold.
For small mixing angles, partial or complete decoherence can be induced by a
parametric resonance, introducing a new time scale to the problem, the final
outcome depending on the spectrum and mixing angle. We derive an analytic
relation that allows us to calculate the late-time degree of coherence based on
the spectrum alone.

18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con