Measurement of the generalized spin polarizabilities of the neutron in the low $Q^2$ region
V. Sulkosky, C. Peng, J. -P. Chen, A. Deur, S. Abrahamyan, K. A. Aniol, D. S. Armstrong, T. Averett, S. L. Bailey, A. Beck, P. Bertin, F. Butaru, W. Boeglin, A.… 展开作者
V. Sulkosky, C. Peng, J. -P. Chen, A. Deur, S. Abrahamyan, K. A. Aniol, D. S. Armstrong, T. Averett, S. L. Bailey, A. Beck, P. Bertin, F. Butaru, W. Boeglin, A. Camsonne, G. D. Cates, C. C. Chang, Seonho Choi, E. Chudakov, L. Coman, J. C Cornejo, B. Craver, F. Cusanno, R. De Leo, C. W. de Jager, J. D. Denton, S. Dhamija, R. Feuerbach, J. M. Finn, S. Frullani, K. Fuoti, H. Gao, F. Garibaldi, O. Gayou, R. Gilman, A. Glamazdin, C. Glashausser, J. Gomez, J. -O. Hansen, D. Hayes, B. Hersman, D. W. Higinbotham, T. Holmstrom, T. B. Humensky, C. E. Hyde, H. Ibrahim, M. Iodice, X. Jiang, L. J. Kaufman, A. Kelleher, K. E. Keister, W. Kim, A. Kolarkar, N. Kolb, W. Korsch, K. Kramer, G. Kumbartzki, L. Lagamba, V. Laine, G. Laveissiere, J. J. Lerose, D. Lhuillier, R. Lindgren, N. Liyanage, H. -J. Lu, B. Ma, D. J. Margaziotis, P. Markowitz, K. McCormick, M. Meziane, Z. -E. Meziani, R. Michaels, B. Moffit, P. Monaghan, S. Nanda, J. Niedziela, M. Niskin, R. Pandolfi, K. D. Paschke, M. Potokar, A. Puckett, V. A. Punjabi, Y. Qiang, R. Ransome, B. Reitz, R. Roche, A. Saha, A. Shabetai, S. Sirca, J. T. Singh, K. Slifer, R. Snyder, P. Solvignon, R. Stringer, R. Subedi, W. A. Tobias, N. Ton, P. E. Ulmer, G. M. Urciuoli, A. Vacheret, E. Voutier, K. Wang, L. Wan, B. Wojtsekhowski, S. Woo, H. Yao, J. Yuan, X. Zhan, X. Zheng, L. Zhu
备注：
V1: initial version submitted to Nature Physics. V2: Published version. 16 pages, 7 figures. Additional material: 4 data tables (18 pages) V3: Typo corrected in author list. Paper content unchanged
Understanding the nucleon spin structure in the regime where the strong interaction becomes truly strong poses a challenge to both experiment and theory. At energy scales below the nucleon mass of about 1 GeV, the intense interaction among the quarks and gluons inside the nucleon makes them highly correlated. Their coherent behaviour causes the emergence of effective degrees of freedom, requiring the application of non-perturbative techniques, such as chiral effective field theory. Here, we present measurements of the neutron's generalized spin-polarizabilities that quantify the neutron's spin precession under electromagnetic fields at very low energy-momentum transfer squared down to 0.035 GeV$^2$. In this regime, chiral effective field theory calculations are expected to be applicable. Our data, however, show a strong discrepancy with these predictions, presenting a challenge to the current description of the neutron's spin properties.
Virtual Compton Scattering and Nucleon Generalized Polarizabilities
本文综述了低能区核子$γ^* N \to N γ$的虚康普顿散射（VCT）。我们回顾了与广义极化率（GP）和模型预测这些观测值的理论形式主义。我们提出的GP提取方法，在实验中使用的方法：基于低能量定理的色散关系和形式主义的方法。然后我们回顾了实验结果，重点介绍了最近的质子广义极化率实验数据所带来的进展，并对低能质子广义极化率领域的研究进行了展望。
Precision Sum Rule for Nucleon Isovector Polarizabilities and the Proton-Neutron Mass Difference
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；School for Theoretical Physics, School of Physics and Electronics, Hunan University（湖南大学物理与电子学院理论物理学院）；Hunan Provincial Key Laboratory of High-Energy Scale Physics and Applications, Hunan University（湖南大学高能标物理与应用湖南省重点实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；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）
Measurement of the Generalized Polarizabilities of the Proton at Intermediate $Q^2$
背景资料：广义极化率（GP）是描述核子结构的重要观测量，目前对这些观测量的测量还很缺乏。目的：本文介绍了一个虚拟的康普顿散射实验的细节，在A1设置在美因茨的Microtron通过研究$e p \to e p γ$反应。本文着重于分析的某些方面。方法：该实验提取了$P_{LL} -P_{TT} / ε$和$P_{LT}$结构函数，以及质子的电磁GP，四动量转移平方$Q^2$的三个新值：0.10，0.20和0.45 GeV $^2$。结果：强调了实验参数校正的重要性。测量的$e p \to e p γ$截面的行为，并与理论进行比较。极化率拟合的详细研究揭示了它们的复杂性的一部分，与低能量膨胀的高阶项有关。结论：所提出的方面是有助于最大限度地减少系统的不确定性和提高物理结果的精度的元素。
Virtual Compton Scattering and the Generalized Polarizabilities of the Proton at Q^2=0.92 and 1.76 GeV^2
质子上的虚康普顿散射（Virtual Compton Scattering，E-C）已经在Jefferson实验室使用专有的光子电产生反应（e p --> e p gamma）进行了研究。本文详细介绍了导致确定结构函数P_LL-P_TT/Q^2和P_LT的分析，以及在四动量转移平方Q^2= 0.92和1.76 GeV^2时的电磁广义极化率（GP）α_E（Q^2）和β_M（Q^2）。这些数据，再加上在较低动量下的质子自旋共振实验的结果，有助于建立一个在整个测量的Q^2范围内质子的电磁GP的连贯图像，并指出它们的非平凡行为。
A new measurement of the structure functions $P_{LL}-P_{TT}/epsilon$ and $P_{LT}$ in virtual Compton scattering at $Q^2=$ 0.33 (GeV/c)$^2$
在$Q^2 = 0.33$（GeV/c）$^2$处测量了$ep \to e' p' γ$反应的截面。该实验使用MAMI加速器的电子束和A1合作的标准检测器设置进行。用虚康普顿散射的低能定理分析了截面，得到了质子广义极化率线性组合的两个结构函数$P_LL}-P_{TT}/epsilon$和$P_{LT}$的新的确定.我们发现，在相同的$Q^2$的值比以前的调查稍大。然而，这种差异纯粹是由于我们对数据进行了更精细的分析。这些结果倾向于证实广义极化率的非平凡的$Q^2$演化，并呼吁在低$Q^2$区域（$\le$ 1（GeV/c）$^2$）进行更多的测量。
Photon-nucleon entanglement in Compton scattering at low and high energies
Physics Department, Brookhaven National Laboratory（布鲁克海文国家实验室物理系）；RIKEN BNL Research Center, Brookhaven National Laboratory（理化学研究所布鲁克海文研究中心）；Université Paris-Saclay - CEA - IRFU（巴黎萨克雷大学-法国原子能和替代能源委员会-核物理研究所）；Center for Frontiers in Nuclear Science, Stony Brook University（纽约州立大学石溪分校核科学前沿中心）
