We show that two P11 nucleon resonance poles near the pi Delta threshold, obtained in several analyses, are stable against large variations of parameters within a dynamical coupled-channels analysis based on meson-exchange mechanisms. By also performing an analysis based on a model with a bare nucleon state, we find that this two-pole structure is insensitive to the analytic structure of the amplitude in the region below pi N threshold. Our results are M_pole = (1363^{+9}_{-6} -i79^{+3}_{-5}) MeV and (1373^{+12}_{-10} -i114^{+14}_{-9}) MeV. We also demonstrate that the number of poles in the 1.5 GeV < W < 2 GeV region could be more than one, depending on how the structure of the single-energy solution of SAID is fitted. For three-pole solutions, our best estimated result of a pole near N(1710) listed by Particle Data Group is (1829^{+131}_{-65} -i192^{+88}_{-110}) MeV which is close to the results of several previous analyses. Our results indicate the need of more accurate pi N reaction data in the W > 1.6 GeV region for high precision resonance extractions.
英文摘要：
We show that two P11 nucleon resonance poles near the pi Delta threshold, obtained in several analyses, are stable against large variations of parameters within a dynamical coupled-channels analysis based on meson-exchange mechanisms. By also performing an analysis based on a model with a bare nucleon state, we find that this two-pole structure is insensitive to the analytic structure of the amplitude in the region below pi N threshold. Our results are M_pole = (1363^{+9}_{-6} -i79^{+3}_{-5}) MeV and (1373^{+12}_{-10} -i114^{+14}_{-9}) MeV. We also demonstrate that the number of poles in the 1.5 GeV < W < 2 GeV region could be more than one, depending on how the structure of the single-energy solution of SAID is fitted. For three-pole solutions, our best estimated result of a pole near N(1710) listed by Particle Data Group is (1829^{+131}_{-65} -i192^{+88}_{-110}) MeV which is close to the results of several previous analyses. Our results indicate the need of more accurate pi N reaction data in the W > 1.6 GeV region for high precision resonance extractions.
Extraction of Meson Resonances from Three-pions Photo-production Reactions
我们研究了从核子上的三π介子光生反应的Dalitz图分析中提取的介子共振性质的模型依赖性。在Phys. Rev. D 84，114019（2011）中开发的酉模型中，我们生成Dalitz图分布作为数据来执行同量异位素模型拟合，这与之前对三π介子产生反应的大多数分析相似。结果表明，两种模型的共振位置吻合较好，但在分叉点附近存在共振极点。从这两个模型中提取的共振振幅的残差和通常的Breit-Wigner程序只对窄宽度的孤立共振一致。对于重叠共振，大多数提取的残留物可能完全不同。我们的研究结果表明，即使有高精度的数据，共振提取应该是基于模型的振幅参数化的三粒子么正性条件的约束。
Neuro-dispersive extractions of light-meson resonances
Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of California, Berkeley（加州大学伯克利分校）；The College of William & Mary（威廉与玛丽学院）；Università degli Studi di Messina（墨西拿大学）；Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器设施）；Old Dominion University（老道明大学）；Universidad Nacional de Educación a Distancia (UNED)（西班牙国立远程教育大学）；INFN Sezione di Catania（意大利国家核物理研究所卡塔尼亚分部）
Self-consistent spectral framework for inclusive nonelastic breakup: The Trojan-horse method as its sub-Coulomb resonant limit
School of Physics Science and Engineering, Tongji University（同济大学物理科学与工程学院）；Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所南方核科学理论中心）
Hunting resonance poles with Rational Approximants
基于数学上定义良好的Padé理论，提出了一种理论上安全的提取极点质量和共振宽度的新方法。特别地，由于Montessus de Ballore定理，我们能够展开振幅的第二黎曼单，以搜索复平面中谐振极点的位置。该方法是系统的，并提供了一个独立于模型的处理的预测和相应的近似误差。这封信部分涵盖了作者在2010年6月28日至7月3日在法国蒙彼利埃举行的第15届国际量子色动力学会议：QCD 10（25周年纪念）和2010年8月30日至9月3日在西班牙马德里举行的夸克禁闭和强子谱IX上提交的材料。
On the phase-shift parameterization and ANC extraction from elastic-scattering data
基于有效射程函数的Padé展开式，提出了一种计算带电原子核弹性散射相移的参数化方法。该方法是潜在的独立和输入减少到实验相移和束缚态能量。它允许一个简单的计算共振特性和渐近归一化常数（ANC）的亚阈值束缚态。我们分析了$^{12}$ C $+α$体系的$1^-$和$2^+$相移，并提取了相应束缚态的ANC.对于$1^-$状态，相对于目前可用的最佳值，获得了3倍的改进，在可达性方面获得了10倍的改进。对于$2^+$状态，由于实验相移上相对较大的误差条，没有获得改善。
