Partial wave analysis of events in proton-proton reactions for energies between 1.9 and 3.5 GeV

核子共振的谱和性质为QCD的非微扰扇区提供了重要的见解。研究这些核子共振的适当方法是使用部分波分析（PWA），其中实验数据被分解为不同部分波振幅的总和。为此，过去主要考虑介子弹性和非弹性反应的数据。最近，研究p+p反应也成为可能，特别是通过p+p（到）p+ Lambda + K反应产生的开放奇性引起了人们的极大兴趣。这些反应确实可以为N（星）共振光谱提供新的和互补的见解，这些共振与Lambda Kaon衰变通道有重要的耦合。此外，关于p KLambda最终态的数据在奇异粒子的背景下非常有趣，比如预测的ppK。对p+p反应中这些态的存在及其性质的研究有助于提高对阈值以下低能反介子核子动力学的理解。在此提议的项目中，我们打算调查不同能量下pKLambda生产的各种现有数据，并旨在将所有这些数据同时与波恩-加特奇纳PWA计划相匹配。为此，我们首先将PWA分别应用于每个数据集，这样我们就可以得到哪个N（星）共振在哪个能量下做出贡献的第一个评估。之后，我们将合并所有的数据集并同时进行拟合。通过这种方法，我们可以提取出不同部分波振幅的能量依赖关系。最后，我们还想在PWA框架中实现一个ppK波，这样我们就可以测试数据为这种奇异状态的存在留下了多少空间。所提出的分析结果将有助于提高对N（星）共振谱的理解，它也将有助于解决关于存在或不存在的克子核团簇的难题，其中ppK只是最简单的表示。该项目为两年半的博士后课题。

The spectrum and the properties of nucleon resonances provide important insight into the non-perturbative sector of QCD. A proper way to investigate these nucleon resonances is to use a Partial-Wave-Analysis (PWA), where experimental data are decomposed into a sum of different partial wave amplitudes. For this purpose, mainly data on pion Nucleon elastic and inelastic reactions were considered in the past. Recently, it became also possible to study p+p reactions, where especially the production of open strangeness via the reaction p+p (to) p+ Lambda + K attracts a lot of interest. These reactions can indeed deliver new and complementary insight into the spectrum of N(star) resonances with a significant coupling to the Lambda Kaon decay channel. Furthermore, data on the p KLambda final state are extremely interesting in the context of strange exotic particles, like the predicted ppK.The study of the existence and the properties of such states in p+p reactions can contribute to an improved understanding of the low energy anti kaon nucleon dynamics below threshold. In herewith proposed project we intend to investigate various existing data on pKLambda production at different energies, and aim to fit all these data simultaneously with the Bonn-Gatchina PWA program. For this purpose, we will first apply the PWA to each data set separately, so that we get a first evaluation of which N(star) resonances contribute at which energy. Afterwards, we will combine all the data sets and fit them simultaneously. In this way we can extract the energy dependence for the different partial wave amplitudes. Finally, we also want to implement a ppK wave in the PWA framework, so that we can test how much room the data leave for the existence of such an exotic state.The results of the proposed analysis will contribute to an improved understanding of the N(star) resonance spectrum and it will also help to solve the puzzle about the existence or non-existence of kaonic-nuclear clusters, where the ppK is only the is only the simplest representation. The project shall be topic of a two and a half years Post Doc position.