标题： 中微子振荡对超新星遗迹中微子背景的影响 显示英文标题

标题： Effects of Neutrino Oscillation on the Supernova Relic Neutrino Background

摘要： 我们研究了中微子的振荡或转换在多大程度上增强了超新星遗迹中微子背景（SRN）在超级神冈探测器（SK）中的预期事件率。 SRN \bar \nu _e 可以通过 MSW 振荡几乎完全与 \nu _\mu 类型的中微子相互交换，在倒序质量等级下， \Delta m^2 ≈ 10^{-8}--10^5 [eV^2]，或者通过马约拉纳中微子的磁矩实现，其中 \mu _\nu ≥ 10^{-12} \mu _B 和 \Delta m^2 ≈ 10^{-4}--10^0 [eV^2]。 在标准的SRN通量计算中，在15–40 MeV可观测能量范围内，如果所有的\bar \nu _e都被替换成\nu _\mu 类似中微子，那么在SK处\bar \nu _e 的事例率可以由 1.2 年^{-1}提高到 2.4 年^{-1}。 这种增强在高能区尤为显著（\gtilde 25 MeV）。在天体物理乐观计算的情况下，事件率可高达9.4年^{-1}。考虑到各种天体物理不确定性，如果不发生振荡，SRN事件的理论上限约为5年^{-1}，因此，如果在SK中观测到每年超过5个事件以及显著更硬的能谱，我们可能不得不诉诸中微子振荡。 显示英文摘要

摘要： We investigate to what extent the oscillation or conversion of neutrinos enhances the expected event rate of the supernova relic neutrino background (SRN) at the Super-Kamiokande detector (SK). The SRN \bar\nu_e's can be almost completely exchanged with \nu_\mu-like neutrinos by the MSW oscillation under the inverse mass hierarchy with \Delta m^2 ~ 10^{-8}--10^5 [eV^2], or by the magnetic moment of Majorana neutrinos with \mu_\nu >~ 10^{-12} \mu_B and \Delta m^2 ~ 10^{-4}--10^0 [eV^2]. In the standard calculation of the SRN flux, the event rate of the SRN \bar\nu_e's at the SK in the observable energy range of 15--40 MeV can be enhanced from 1.2 yr^{-1} to 2.4 yr^{-1} if all \bar\nu_e's are exchanged with \nu_\mu-like neutrinos. The enhancement is prominent especially in the high energy range (\gtilde 25 MeV). In the astrophysically optimistic calculation, the event rate becomes as high as 9.4 yr^{-1}. Because the theoretical upper bound of the SRN events without oscillation is about 5 yr^{-1} taking account of the various astrophysical uncertainties, we might have to resort to the neutrino oscillation if more than 5 events in a year, as well as a significantly harder spectrum, were observed in the SK.