论文标题

Icecube中微子天文台的无菌中微子搜索

Sterile Neutrino Searches at the IceCube Neutrino Observatory

论文作者

Axani, Spencer

论文摘要

Icecube中微子天文台能够通过剥削物质增强的共振中微子振荡现象对无菌中微子进行独特的搜索。随着大气中的中微子通过地球内的致密材料,预测中性电流弹性向前散射将诱导过渡到无菌状态。 本论文通过在若恩中微子事件的重建能量和天顶方向上寻找光谱差异来提出两个3+1无菌中微子分析,这表明过渡到无菌状态。第一个搜索探索参数空间$δ$ m $^2_ {41} $和sin $^2 $(2 $θ_{24} $),对3+1无菌中微子假设的全球最佳拟合区域具有相关的敏感性。第二次搜索通过SIN $^2 $(2 $θ_{24} $)和SIN $^2 $(2 $θ_{34} $)进行扫描,并在振动中平均分别为高 - $Δ$ m $^$ m $^2_ {2_ {41} $($ m $^$^$^$ m $ m $ m $ m $ m $ m $^$ m $^$^$^$^$^$^$ \ $ \ g g gtr)分析是使用改进的事件选择进行的,发现从八年的IceCube数据中提取了305,891个重建经过重建的MUON中微子事件,其样品纯度高于99.9 \%。还讨论了新颖的仿真技术,以及更新的校准以及对系统不确定性的重新评估。 第一个分析发现,最适合的无菌假设点为$δ$ m $^2_ {41} $ = 4.47 ev $^2 $和sin $^2 $($θ_{24})$ = 0.10,与8 \%置信度的无抗假设一致。第二个分析发现,在sin $^2 $($θ_{34})$ = 0.40,sin $^2 $($θ_{24})$ = 0.006处的最佳拟合无菌假设,与19 \%置信度的零假设一致。 %并使用MUON NETRINO消失在世界测量方面有了显着改善。

The IceCube Neutrino Observatory is capable of performing a unique search for sterile neutrinos through the exploitation of a matter enhanced resonant neutrino oscillation phenomena. As atmospheric muon neutrinos pass the dense material within the Earth, neutral current elastic forward scattering is predicted to induce a transition into a sterile state. This thesis presents two 3+1 sterile neutrino analyses by searching for spectral differences in the reconstructed energy and zenith direction of muon neutrino events, indicative of a transition into a sterile state. The first search probes the parameter space $Δ$m$^2_{41}$ and sin$^2$(2$θ_{24}$) with relevant sensitivity to the global best fit region for a 3+1 sterile neutrino hypothesis. The second search performs a scan through sin$^2$(2$θ_{24}$) and sin$^2$(2$θ_{34}$) in the oscillation averaged out region of high-$Δ$m$^2_{41}$ ($Δ$m$^2_{41}$ $\gtrsim$ 10eV$^2$). The analyses are performed using an improved event selection, which was found to extract 305,891 well reconstructed muon neutrino events with a sample purity above 99.9\%, from eight years of IceCube data. Novel simulation techniques, along with updated calibration, and a re-assessment of the systematic uncertainties are also discussed. The first analysis finds a best fit sterile hypothesis point at $Δ$m$^2_{41}$ = 4.47eV$^2$ and sin$^2$($θ_{24})$ =0.10, consistent with the no-sterile hypothesis at the 8\% confidence level. The second analysis finds a best fit sterile hypothesis at sin$^2$($θ_{34})$ = 0.40, sin$^2$($θ_{24})$ = 0.006, consistent with the null hypothesis at the 19\% confidence level. % and provides a significant improvement in the worlds measurements using muon neutrino disappearance.

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