Measurement of beam asymmetry for $π^-Δ^{++}$ photoproduction on the proton at $E_γ$=8.5 GeV
GlueX Collaboration, S. Adhikari, C. S. Akondi, A. Ali, M. Amaryan, A. Asaturyan, A. Austregesilo, Z. Baldwin, F. Barbosa, J. Barlow, E. Barriga, R. Barsotti, T… 展开作者
GlueX Collaboration, S. Adhikari, C. S. Akondi, A. Ali, M. Amaryan, A. Asaturyan, A. Austregesilo, Z. Baldwin, F. Barbosa, J. Barlow, E. Barriga, R. Barsotti, T. D. Beattie, V. V. Berdnikov, T. Black, W. Boeglin, W. J. Briscoe, T. Britton, W. K. Brooks, B. E. Cannon, E. Chudakov, S. Cole, O. Cortes, V. Crede, M. M. Dalton, T. Daniels, A. Deur, S. Dobbs, A. Dolgolenko, R. Dotel, M. Dugger, R. Dzhygadlo, H. Egiyan, T. Erbora, A. Ernst, P. Eugenio, C. Fanelli, S. Fegan, J. Fitches, A. M. Foda, S. Furletov, L. Gan, H. Gao, A. Gasparian, C. Gleason, K. Goetzen, V. S. Goryachev, L. Guo, H. Hakobyan, A. Hamdi, G. M. Huber, A. Hurley, D. G. Ireland, M. M. Ito, I. Jaegle, N. S. Jarvis, R. T. Jones, V. Kakoyan, G. Kalicy, M. Kamel, V. Khachatryan, M. Khatchatryan, C. Kourkoumelis, S. Kuleshov, A. LaDuke, I. Larin, D. Lawrence, D. I. Lersch, H. Li, W. B. Li, B. Liu, K. Livingston, G. J. Lolos, K. Luckas, V. Lyubovitskij, D. Mack, H. Marukyan, V. Matveev, M. McCaughan, M. McCracken, W. McGinley, C. A. Meyer, R. Miskimen, R. E. Mitchell, K. Mizutani, V. Neelamana, F. Nerling, L. Ng, A. I. Ostrovidov, Z. Papandreou, C. Paudel, P. Pauli, R. Pedroni, L. Pentchev, K. J. Peters, W. Phelps, E. Pooser, J. Reinhold, B. G. Ritchie, J. Ritman, G. Rodriguez, D. Romanov, C. Romero, C. Salgado, S. Schadmand, A. M. Schertz, A. Schick, R. A. Schumacher, J. Schwiening, X. Shen, M. R. Shepherd, A. Smith, E. S. Smith, D. I. Sober, A. Somov, S. Somov, O. Soto, J. R. Stevens, I. I. Strakovsky, B. Sumner, K. Suresh, V. V. Tarasov, S. Taylor, A. Teymurazyan, A. Thiel, G. Vasileiadis, T. Whitlatch, N. Wickramaarachchi, M. Williams, Y. Yang, J. Zarling, Z. Zhang, Z. Zhao, J. Zhou, Q. Zhou, X. Zhou, B. Zihlmann
本文报道了在8.2- 8.8 GeV光子束能量范围内，利用GREX实验数据测量了反应$\vecγ p \rightarrow π^- Δ^{++}$的$π^-$光生束不对称性。测量的不对称性$Σ$作为一个功能的四动量转移$t$的$Δ^{++}$和相比，唯象模型。我们发现$Σ$作为$t$的函数而变化：在较小的值处为负，在较高的$|t|$值处为正。该反应理论上可以描述为$t$通道粒子交换，需要赝标量，矢量和张量中介。特别是，这种反应需要电荷交换，使我们能够探测π介子交换和高阶修正的意义，在低动量转移的一π介子交换。常规介子的约束产生机制可能有助于非常规介子的寻找和研究。这是在这个能量下对过程的第一次测量。
英文摘要：
We report a measurement of the $π^-$ photoproduction beam asymmetry for the reaction $\vecγ p \rightarrow π^- Δ^{++}$ using data from the GlueX experiment in the photon beam energy range 8.2--8.8 GeV. The asymmetry $Σ$ is measured as a function of four-momentum transfer $t$ to the $Δ^{++}$ and compared to phenomenological models. We find that $Σ$ varies as a function of $t$: negative at smaller values and positive at higher values of $|t|$. The reaction can be described theoretically by $t$-channel particle exchange requiring pseudoscalar, vector, and tensor intermediaries. In particular, this reaction requires charge exchange, allowing us to probe pion exchange and the significance of higher-order corrections to one-pion exchange at low momentum transfer. Constraining production mechanisms of conventional mesons may aid in the search for and study of unconventional mesons. This is the first measurement of the process at this energy.
Measurement of the beam asymmetry $Σ$ and the target asymmetry $T$ in the photoproduction of $ω$ mesons off the proton using CLAS at Jefferson Laboratory
Beam asymmetry for pi+ and pi0 photoproduction on the proton for photon energies from 1.102 to 1.862 GeV
用CEBAF大接收谱仪（CLAS）和能量为1.102 - 1.862 GeV的线偏振光子束测量了γ p -> p π 0和γ p -> n π +反应的束流不对称性。本文介绍了一种从实验数据中提取光束非对称性的傅里叶矩技术。这里报道的结果具有更高的精度和更精细的能量分辨率比以前的测量。我们的两个π介子反应的数据似乎有利于SAID和Bonn-Gatchina散射分析的老美因茨MAID预测。在将目前的光束不对称性集合并入世界数据库之后，用SAID分析进行的探索性拟合表明，与先前拟合相比的最大变化是针对Delta（1700）3/2-和Delta（1905）5/2+状态的性质。
Helicity-Dependent Angular Distributions for Double-Charged-Pion Photoproduction
在Jefferson实验室Hall B使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束研究了γ p -> p pi+ pi-反应中的2 π介子光生。测量了末态粒子的角分布与束流螺旋度的关系。大横截面的不对称性，已被发现表现出强烈的敏感性的反应的运动学，并与初步模型计算Mokeev和罗伯茨。
Helicity-Dependent Angular Distributions in Double-Charged-Pion Photoproduction
在杰斐逊实验室大厅B，使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束，研究了伽马+ p -> p + pi^+ + pi^-反应中的双π介子光生。由于CLAS探测器的大角度接受能力，测量了末态粒子的完全束螺旋度相关的角分布。大截面的不对称性表现出强烈的灵敏度的反应的运动学，并提供有价值的信息的反应动力学。初步结果。
Geometry-induced azimuthal anisotropy in coherent $J/ψ$ photoproduction
Fudan University（复旦大学）；Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University（上海理论核物理研究中心，NSFC与复旦大学）；Hangzhou Normal University（杭州师范大学）；Shandong University（山东大学）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
