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arXiv 0905.3658hep-phastro-ph.SR
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核塌缩超新星中具有磁矩的中微子自旋翻转

Spin flip of neutrinos with magnetic moment in core-collapse supernova

Oleg Lychkovskiy, Sergei Blinnikov

摘要:

具有磁矩的中微子在散射带电粒子时会发生手征翻转。这种效应可能会导致重要的后果的动力学和核心坍缩超新星的中微子信号。如果中微子是狄拉克费米子,那么由手征翻转引起的nu_L->nu_R跃迁将导致无菌右手中微子的发射。这些中微子的典型能量很高,E ~(100-200)MeV。无论是在坍缩恒星内部还是在星际空间,中微子在磁场中的自旋进动都可能导致后向跃迁nu_R->nu_L。这两种可能性都很有趣。在前一种情况下,高能中微子可以向超新星的包层提供额外的能量,这可以帮助超新星爆炸。在后一种情况下,高能中微子可能与“正常”超新星中微子信号同时被探测到,这将是狄拉克中微子磁矩的确凿证据。我们报告的超新星右手中微子光度的计算结果反弹后250毫秒。它们允许改进右手中微子发射的能量的估计。本文还估算了水切伦科夫探测器对狄拉克中微子磁矩的灵敏度。当μ_Dirac=10^{-13} μ_B时,Super-Kamiokande预计至少能探测到来自银河系超新星爆炸的几个高能事件。并简要讨论了Majorana中微子磁矩的情况。本文指出,当μ_Majorana~10^{-12} μ_B时,自旋翻转可使电子中微子与非电子反中微子迅速平衡.这可能会导致超新星物理学的各种后果。

英文摘要:

Neutrino with magnetic moment can experience a chirality flip while scattering off charged particles. This effect may lead to important consequences for the dynamics and the neutrino signal of the core-collapse supernova. It is known that if neutrino is a Dirac fermion, then nu_L->nu_R transition induced by the chirality flip leads to the emission of sterile right-handed neutrinos. The typical energies of these neutrinos are rather high, E ~ (100-200)MeV. Neutrino spin precession in the magnetic field either inside the collapsing star or in the interstellar space may lead to the backward transition, nu_R->nu_L. Both possibilities are known to be interesting. In the former case high-energy neutrinos can deliver additional energy to the supernova envelope, which can help the supernova to explode. In the latter case high-energy neutrinos may be detected simultaneously with the "normal" supernova neutrino signal, which would be a smoking gun for the Dirac neutrino magnetic moment. We report the results of the calculation of the supernova right-handed neutrino luminosity up to 250 ms after bounce. They allow to refine the estimates of the energy emitted in right-handed neutrinos. Also the sensitivity of water Cherenkov detectors to the Dirac neutrino magnetic moment is estimated. For mu_Dirac=10^{-13}mu_B Super-Kamiokande is expected to detect at least few high-energy events from a galactic supernova explosion. Also we briefly discuss the case of Majorana neutrino magnetic moment. It is pointed out that spin flips may quickly equilibrate electron neutrinos with non-electron antineutrinos if mu_Majorana~10^{-12}mu_B. This may lead to various consequences for supernova physics.

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