The $Λp$ interaction close to the $ΣN$ threshold is considered. Specifically, the pronounced structure seen in production reactions like $K^-d \to π^- Λp$ and $pp\to K^+ Λp$ around the $ΣN$ threshold is analyzed. Modern interaction models of the coupled $ΛN - ΣN$ systems generate such a structure either due to the presence of a (deuteron-like) unstable bound state or of an inelastic virtual state. %
A determination of the position of the prominent peak as observed in various experiments for the two aforementioned reactions leads to values that agree quite well with each other. Furthermore, the deduced mean value of $2128.7\pm 0.3$ MeV for the peak position coincides practically with the threshold energy of the $Σ^+ n$ channel. This supports the interpretation of the structure as a genuine cusp, signaling an inelastic virtual state in the $^3S_1-^3D_1$ partial wave of the $ΣN$ isospin 1/2 channel. %
There is also evidence for a second peak (or shoulder) in the data sets considered which appears at roughly 10-15 MeV above the $ΣN$ threshold. However, its concrete position varies significantly from data set to data set and, thus, a theoretical interpretation is difficult.
Electrodisintegration of Deuteron into Dark Matter and Proton Close to Threshold
我们讨论了调查的暗物质衰变模式的中子，提出了Fornal和Grinstein（物理评论快报。120 191801（2018））和Ivanov等人（arXiv：1806.10107 [hep-ph]）通过分析氘核d电蜕变成接近阈值的暗物质费米子chi和质子p，解决了中子寿命异常问题。我们计算了反应e^- + d -> x + p + e^-的三重微分截面，并建议在符合实验中寻找这样一个暗物质通道，该实验研究了氘核e^- + d -> n + p + e^-电蜕变为中子n和接近阈值的质子，同时电子、质子和中子符合地出射。中子信号的缺失应该证明探测到了暗物质费米子。
Study of the $η$-nucleus interaction in the $p d \to ^3He η$ reaction near threshold
详细研究了在接近阈值的$p d \to ^3$ He $ η$反应中$η$ -核终态相互作用（FSI）的影响. FSI通过$η^3$ He弹性散射的T矩阵结合，使用几个身体方程构造。该T矩阵解释了$η$ -核散射中的离壳效应和结合效应。只有在包括FSI之后，才能再现阈值附近的$p d \to ^3$ He $ η$反应的数据的能量依赖性。离壳效应和束缚效应在$η^3$ He散射中是重要的。考虑到基本$η$ -核子相互作用知识的不确定性，还讨论了$ p d \to ^3$ He $ η$截面对基本t矩阵$t_{ηN \to ηN}$的不同处方的敏感性。
On strangeness production in the reactions pp -> p Lambda^0 K^+ and pn -> n Lambda^0 K^+ near threshold
计算了pp -> p λ ^0 K ^+和pn -> n λ ^0 K ^+反应的截面。截面的理论比值R = sigma（pn -> n Lambda^0K^+）/ sigma（pp ->pΛ^0K^+）= 3表明，在奇异产生N Lambda^0K^+的阈值附近，pn相互作用相对于pp相互作用的增强。这种增强是由在同位旋单重态中的np相互作用的贡献引起的，其强于在同位旋三重态中的$pn$相互作用。为了证实这个结果，我们计算了反应pp -> pp pi ^0，pi ^0 p -> Lambda ^0 K^+和pi^-p -> Lambda ^0 K ^0在末态阈值附近的截面。理论截面与实验数据吻合较好。
a0+(980)-resonance production in pp->dK+Kbar0 reactions close to threshold
在COSY-Juelich使用ANKE在高于（K+ Kbar 0）阈值Q=46 MeV的过剩能量下研究了反应pp->d K+ Kbar 0。从检测到的重合dK+对中，识别出约1000个Kbar 0缺失的事件，对应于sigma（pp->d K+ Kbar 0）=（38 +/- 2（stat）+/- 14（syst））nb的总截面。不变的质量和角分布已被联合分析，并揭示了两个K介子之间的s波优势，伴随着p波之间的氘核和K介子系统。这可以用a0+（980）-共振产生来解释。
