7.4. Symmetric Neutrino Flavor Evolution¶

7.4.1. Neutrino Gas¶

The simplest symmetric neutrino flavor evolution senario is homogeneous and isotropic neutrino gas.

Large matter density will suppress the flavor conversions because it will keep the flavor isospin aligned with it. However, as the matter density drops below some value, we expect the flavor isospin to be unstable.

For such a reason, we expect the flavor conversion to follow matter only evolution (MSW) then phase transform to flavor conversion of neutrino self-interactions, in a model with decreasing matter density and neutrino number density.

For NH we have the $$\nu$$-enhenced MSW flavor transformation [Duan2010].

7.4.2. Bulb Model¶

The (in)famous neutrino bulb model is a model that describe the neutrino flavor evolution for neutrinos emitted homogeneously and isotropically, except that we only need to consider half of the sphere.

7.4.3. References and Notes¶

 [Duan2010] Duan, H., Fuller, G. M., & Qian, Y.-Z. (2010). Collective Neutrino Oscillations. Annual Review of Nuclear and Particle Science, 60(1), 569–594.

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