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arXiv 1108.2630hep-ph
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下行τ中微子作为探测暗物质的新前景

Downward-going tau neutrinos as a new prospect of detecting dark matter

Nicolao Fornengo, Viviana Niro

备注：
24 pages, 10 figures. Version published in JHEP. Figures revisited with inclusion of galactic neutrino background. Main results and conclusions unchanged
发表信息：
JHEP, Volume 2011, Number 11, 133
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摘要：

被困在太阳中的暗物质产生各种各样的中微子流，这些中微子在传播出太阳并从产生点振荡到探测器之后到达地球。典型的信号是指μ子中微子成分，由中微子探测器中的上行μ子通量组成。相反，我们提出了一个新的签名：在暗物质的信号，这是几乎是背景免费的向下去的方向，因为大气中微子中的τ中微子量是可以忽略不计的可能性，并在下行基线大气μ介子中微子没有时间大幅度振荡。通过研究带电τ中微子相互作用和随后的τ衰变产生的强子簇射，分析了Cherenkov探测器研究太阳中暗物质湮灭（或衰变）产生的下行τ中微子的前景。我们讨论了各种来源的背景（即小τ中微子在大气中的组成部分，无论是从直接生产和振荡; τ中微子从太阳日冕相互作用;银河系的τ中微子组件）以及由于错误识别的电子和μ子事件的背景来源。我们发现，下行的tau中微子信号具有潜在的非常好的前景，Mton规模的切伦科夫探测器，主要的限制是非tau事件的错误识别水平，需要保持在百分比的水平。Mton尺度探测器每年可能收集到几十个事件（取决于暗物质质量和湮灭/衰变通道），并且在Mton探测器上曝光几年，可能会在20到300 GeV的范围内发现5 sigma重要性的暗物质。

英文摘要：

Dark matter trapped in the Sun produces a flux of all flavors of neutrinos, which then reach the Earth after propagating out of the Sun and oscillating from the production point to the detector. The typical signal which is looked at refers to the muon neutrino component and consists of a flux of up-going muons in a neutrino detector. We propose instead a novel signature: the possibility of looking at the tau neutrino component of the dark matter signal, which is almost background-free in the downward-going direction, since the tau neutrino amount in atmospheric neutrinos is negligible and in the down-going baseline atmospheric muon-neutrinos have no time to sizably oscillate. We analyze the prospects of studying the downward-going tau neutrinos from dark matter annihilation (or decay) in the Sun in Cherenkov detectors, by looking at hadronic showers produced in the charged-current tau neutrino interactions and subsequent tau decay. We discuss the various sources of background (namely the small tau neutrino component in atmospheric neutrinos, both from direct production and from oscillations; tau neutrinos from solar corona interactions; the galactic tau neutrino component) as well as sources of background due to misidentification of electron and muon events. We find that the downward-going tau neutrinos signal has potentially very good prospects for Mton scale Cherenkov detectors, the main limitation being the level of misidentification of non-tau events, which need to be kept at level of percent. Several tens of events per year (depending on the dark matter mass and annihilation/decay channel) are potentially collectible with a Mton scale detector, and a 5 sigma significance discovery is potentially reachable for dark matter masses in the range from 20 to 300 GeV with a few years of exposure on a Mton detector.

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