662 research outputs found
Exact Methods for Self Interacting Neutrinos
The effective many-body Hamiltonian which describes vacuum oscillations and
self interactions of neutrinos in a two flavor mixing scheme under the single
angle approximation has the same dynamical symmetries as the well known BCS
pairing Hamiltonian. These dynamical symmetries manifest themselves in terms of
a set of constants of motion and can be useful in formulating the collective
oscillation modes in an intuitive way. In particular, we show that a neutrino
spectral split can be simply viewed as an avoided level crossing between the
eigenstates of a mean field Hamiltonian which includes a Lagrange multiplier in
order to fix the value of an exact many-body constant of motion. We show that
the same dynamical symmetries also exist in the three neutrino mixing scheme by
explicitly writing down the corresponding constants of motion.Comment: To appear in the proceedings of CETUP* 201
Axion Production from Landau Quantization in the Strong Magnetic Field of Magnetars
We utilize an exact quantum calculation to explore axion emission from
electrons and protons in the presence of the strong magnetic field of
magnetars. The axion is emitted via transitions between the Landau levels
generated by the strong magnetic field. The luminosity of axions emitted by
protons is shown to be much larger than that of electrons and becomes stronger
with increasing matter density. Cooling by axion emission is shown to be much
larger than neutrino cooling by the Urca processes. Consequently, axion
emission in the crust may significantly contribute to the cooling of magnetars.
In the high-density core, however, it may cause heating of the magnetar.Comment: 14 pages, 3 figure
Invariants of Collective Neutrino Oscillations
We consider the flavor evolution of a dense neutrino gas by taking into
account both vacuum oscillations and self interactions of neutrinos. We examine
the system from a many-body perspective as well as from the point of view of an
effective one-body description formulated in terms of the neutrino polarization
vectors. We show that, in the single angle approximation, both the many-body
picture and the effective one-particle picture possess several constants of
motion. We write down these constants of motion explicitly in terms of the
neutrino isospin operators for the many-body case and in terms of the
polarization vectors for the effective one-body case. The existence of these
constants of motion is a direct consequence of the fact that the collective
neutrino oscillation Hamiltonian belongs to the class of Gaudin Hamiltonians.
This class of Hamiltonians also includes the (reduced) BCS pairing Hamiltonian
describing superconductivity. We point out the similarity between the
collective neutrino oscillation Hamiltonian and the BCS pairing Hamiltonian.
The constants of motion manifest the exact solvability of the system. Borrowing
the well established techniques of calculating the exact BCS spectrum, we
present exact eigenstates and eigenvalues of both the many-body and the
effective one-particle Hamiltonians describing the collective neutrino
oscillations. For the effective one-body case, we show that spectral splits of
neutrinos can be understood in terms of the adiabatic evolution of some
quasi-particle degrees of freedom from a high density region where they
coincide with flavor eigenstates to the vacuum where they coincide with mass
eigenstates. We write down the most general consistency equations which should
be satisfied by the effective one-body eigenstates and show that they reduce to
the spectral split consistency equations for the appropriate initial
conditions.Comment: 26 pages with one figure. Published versio
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