Calculation and experimental analysis of the muon cross sections

在天体粒子物理学中，介子被用作中微子天文学和宇宙射线物理学领域的最终信使粒子。因此，μ介子的相互作用概率正在进入天体物理相关数据的解释，即中微子能谱的确定对于回答大气中微子、提示中微子和天体物理中微子的贡献及其起源的问题至关重要。由于冰立方记录的高μ子速率（高统计精度），现有的μ子截面计算的超系统不确定度对实验的总系统不确定度有很大贡献。在这个项目中，一方面需要用理论物理的方法计算出更高精度的μ子截面。这些新的横截面将在应用小组开发的蒙特卡罗算法提案中实现，以确定剩余不确定性的实验结果。在这方面，已经可以表明，要最小化的系统不确定性的相关贡献来自介子能量损失的概率分布，而不是来自总相互作用概率。同时，利用冰立方应使用记录的大气μ子和中微子诱导μ子的独立数据集，对截面计算的质量进行检验，分别尽可能重建截面。该项目是基于应用小组在计算科学和统计学领域（信号提取的数据挖掘，反问题解决方法的开发，蒙特卡罗模拟的有效方法的开发）和实验和理论物理领域(冰立方中轻子谱重建的数据分析，发展了计算截面QED的方法)。该项目的目标是在三年后显著改善微分和总μ子截面，其不确定性将通过数值和实验手段进行量化。

Muons are used as final messenger particles in astroparticle physics on the fields of neutrino astronomy and cosmic ray physics. Therefore, the interaction probability of muons is entering the interpretation of the astrophysical relevant data, i.e. the determination of neutrino energy spectra important to answer the question for the contributions of atmospheric, prompt and astrophysical neutrinos and their origin. Because of the high muon rate recorded with IceCube (high statistical precision), the this-exceeding systematic uncertainties from the existing calculations of the muon cross sections are contributing significantly to the total systematic uncertainty of the experiment.In this project, on the one hand the muon cross sections shall be calculated with means of theoretical physics to a higher precision. These new cross sections shall be implemented in the Monte Carlo algorithm PROPOSAL, developed by the applying group, to determine the experimental consequences of the remaining uncertainties. In this regard, it could already be shown, that the relevant contributions to the systematic uncertainty to be minimized are coming from the probability distribution of the muon energy losses rather than from the total interaction probability. In parallel, the independent data sets of the atmospheric and neutrino induced muons recorded with IceCube shall be used to test the quality of the cross section calculations, respectively to reconstruct the cross section as far as possible.The project is based on a multitude of preparatory studies of the applying group from the fields of computational science and statistics (data mining for the signal extraction, development of methods for the solution of inverse problems, development of efficient methods for the Monte Carlo simulation) and from the fields of experimental and theoretical physics (data analyses for the reconstruction of the lepton spectra in IceCube, development of methods for the QED calculation of the cross sections).The project aims after three years for a significant improvement of the differential and total muon cross sections, whose uncertainties shall be quantified with numerical and experimental means.