Title: Relic Neutrino Absorption Spectroscopy Show Chinese title

Title: 遗迹中微子吸收光谱学

Abstract: Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10^{21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m_{nu} >~ 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably. Show Chinese abstract

Abstract: 极高能量宇宙中微子与大爆炸遗迹反中微子（反之亦然）通过共振湮灭为Z玻色子，会导致在地球观测到的中微子通量中出现显著的吸收凹陷。 这些凹陷的高能边缘由中微子质量单独通过共振能量确定。 它们的深度由宇宙中微子背景密度、决定宇宙膨胀率的宇宙学参数以及宇宙中微子源的大红移历史决定。 我们研究了在接下来的十年内通过测量中微子通量中的这些吸收凹陷来确定宇宙中微子背景存在的可能性。 作为副产品，我们研究了推断绝对中微子质量尺度的前景。 我们发现，随着目前计划中的中微子探测器（ANITA、Auger、EUSO、OWL、RICE和SalSA）在10^{21} eV以上的相关能量范围内运行，遗迹中微子吸收光谱学成为一种现实的可能性。 然而，这需要存在极其强大的中微子源，这些源应对于核子和高能光子是不透明的，以避免现有的约束。 此外，中微子质量谱必须接近简并，以优化凹陷，这意味着最轻的中微子质量m_{nu} >~ 0.1 eV。 随着第二代中微子探测器的出现，这些严格的要求可以大大放松。