We can understand many recently-discovered features of flavor evolution in dense, self-coupled supernova neutrino and antineutrino systems with a simple, physical scheme consisting of two quasi-static solutions. One solution closely resembles the conventional, adiabatic single neutrino Mikheyev-Smirnov-Wolfenstein (MSW) mechanism, in that neutrinos and antineutrinos remain in mass eigenstates as they evolve in flavor space. The other solution is analogous to the regular precession of a gyroscopic pendulum in flavor space, and has been discussed extensively in recent works. Results of recent numerical studies are best explained with combinations of these solutions in the following general scenario: (1) Near the neutrino sphere, the MSW-like many-body solution obtains. (2) Depending on neutrino vacuum mixing parameters, luminosities, energy spectra, and the matter density profile, collective flavor transformation in the nutation mode develops and drives neutrinos away from the MSW-like evolution and toward regular precession. (3) Neutrino and antineutrino flavors roughly evolve according to the regular precession solution until neutrino densities are low. In the late stage of the precession solution, a stepwise swapping develops in the energy spectra of $ν_e$ and $ν_μ/ν_τ$. We also discuss some subtle points regards adiabaticity in flavor transformation in dense neutrino systems.
Mu-tau neutrino refraction and collective three-flavor transformations in supernovae
本文研究了超新星核心中微子球上方稠密中微子区的三味集体中微子变换。我们发现，两个味道转换驱动的大气质量差和13混合角捕获的全部效果，如果忽略μ介子和τ中微子折射率之间的二阶差。包括这个“μ-τ物质项”后，在密度约为3 x 10^7 g cm^-3时产生共振，这通常会导致电子中微子和反中微子的总体存活概率发生显著变化。这种效应令人惊讶地对最大23-混合的偏差敏感，对于每个八分圆是不同的。
Effects of Random Density Fluctuations on Matter-Enhanced Neutrino Flavor Transitions in Supernovae and Implications for Supernova Dynamics and Nucleosynthesis
Matter-enhanced antineutrino flavor transformation and supernova nucleosynthesis
如果$\barν_e$和$\barν_{μ(τ)}$的真空质量满足$m_{\barν_e}>m_{\barν_{μ(τ)}}$，那么在超新星中可以发生物质增强的反中微子味转换。对于$δm^2> 1$ eV $^2$，这种风味转变可能会影响中微子加热的超新星喷出物中的电子分数$Y_e$。我们指出，这样的味道转换将不会驱动$Y_e>0.5$在$r$过程的核合成时代，在最好的超新星模型，这样的核合成。因此，在中微子加热的超新星喷出物中，物质增强的反中微子味转换$\barν_e\rightleftharpoons\barν_{μ(τ)}$和$r$过程的核合成之间没有明显的冲突。
A Comparison of Boltzmann and Multigroup Flux-Limited Diffusion Neutrino Transport During the Postbounce Shock Reheating Phase in Core Collapse Supernovae
