π ^0 γ衰变通道中Ω介子近阈光生的偏振自由度

第一次观察到欧米茄介子的介质修改

First observation of in-medium modifications of the omega meson

在波恩的ELSA标记光子装置上，利用晶体桶/TAPS实验研究了原子核上ω介子的光生。目的是研究可能的介质修改的欧米茄介子通过反应A（伽马，欧米茄）X。将Nb获得的结果与液氢靶上的参考测量结果进行比较。而反冲，长寿命的介子（π，η和etaprime），衰变的核外，两个数据样本的线形的差异没有观察到，我们发现一个显着的增强对低质量的ω介子与低动量的Nb目标。

能量范围为0.3 GeV < E（gamma）< 3 GeV

Neutral pion photoproduction off protons in the energy range 0.3 GeV < E(gamma) < 3 GeV

单π 0的光生研究了CB-ELSA实验在波恩使用标记的光子能量在0.3和3.0 GeV之间。实验装置涵盖了一个非常大的立体角约98%的4 π。测量了微分截面（d σ）/（d Ω）。角分布中的复杂结构表明在s通道中间态γ p -> N*（Delta*）-> p π 0中产生各种不同的共振。一个综合分析，包括在这封信中提出的数据以及其他数据集揭示了已知的共振和一个新的共振N（2070）D15的证据的贡献。

Extraction of the Pomeron Trajectory from a Global Fit to Exclusive $ρ^0$ Meson Photoproduction Data

Based on data on elastic $ρ^0$ photoproduction from the H1, Omega and ZEUS collaborations, a fit has been performed to extract the value $α_P (t)$ of the pomeron trajectory at fixed values of t from the W dependence of the differential $γp$ cross section $d σ_{γp} (W) / d t$. The data used in the fit cover the range of $8.3 \le W \le 94 GeV$ in $γp$ centre-of-mass energy and $0.01 \le |t| \le 0.95 GeV^2$ in momentum transfer. A linear fit to the resulting values of $α_P (t)$ yields $α_{P,0} =1.0871 \pm 0.0026 (stat.) \pm 0.0030 (syst.)$ for the intercept and $α'_P = 0.126 \pm 0.013 (stat.) \pm…

核子上的π介子光生

Pion photoproduction on the nucleon

$γn \to π^- p$和$γp \to π^+ n$反应是从介子-核子自由度到夸克-胶子自由度跃迁的互斥过程的重要探针。这些过程的截面对于研究夸克计数预测周围的振荡行为也是有利的，因为与其他光子诱导的过程相比，它们随能量的下降相对较慢。在这次演讲中，我们讨论了最近的结果$γp \to π^+ n$和$γn \to π^{-}p$过程从杰斐逊实验室实验E94-104。我们还讨论了一个新的实验中，单$γp \to π^+ n$测量从氢，符合$γn \to π^{-} p$测量从氘准自由运动学的质心能量在2.3 GeV至3.4 GeV之间的精细步骤在一个$90^\circ$的质心角计划。建议的测量将允许详细调查的振荡标度行为的反离子生产过程中。

Searches for Exotic Hadrons at GlueX

The search for hybrid mesons and the detailed study of their spectrum is the primary goal of the GlueX Experiment in Hall D at Jefferson Lab. The identification and study of hybrid mesons promises to provide unique insight into gluonic degrees of freedom in QCD and the nature of confinement. The experiment combines an intense photon beam with linear polarization peaking around 9 GeV incident on a liquid hydrogen target with a nearly hermetic spectrometer, allowing for the comprehensive study of charged and neutral particle final states. The first phase of the experiment has recently concluded,…

Experimental Challenges of the N* Program

The first challenge faced in investigating the strong interaction from partially explored, where meson-cloud degrees of freedom dominate, to still unexplored distance scales, where the dressed-quark contributions are the dominating degrees of freedom, is to find an experiment that allows to measure observables that are probing this evolving nonperturbative QCD regime over the full range. Baryon spectroscopy can establish more sensitively, and in an almost model-independent way, nucleon excitation and non-resonant reaction amplitudes by complete measurements of pseudo-scalar meson photoproducti…

使用CLAS12实验测量近阈值J/ψ光生截面

Measurement of the near-threshold J$/ψ$ photoproduction cross section with the CLAS12 experiment

利用CLAS12探测器测量近阈值J/ψ光生总截面和微分截面，约束非微扰QCD中的产生机制和质子胶子分布。