Defurne M, Mazouz M, Ahmed Z, Albataineh H, Allada K, Aniol K A, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen J-P, de Jager C W, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Huber G M, Hyde C E, Iqbal S, Itard F, Kang Ho, Kang Hy, Kelleher A, Keppel C, Koirala S, Korover I, LeRose J J, Lindgren R, Long E, Magne M, Mammei J, Margaziotis D J, Markowitz P, Martí Jiménez-Argüello A, Meddi F, Meekins D, Michaels R, Mihovilovic M, Muangma N, Muñoz Camacho C, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad M N H, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto M L, Subedi R, Sulkosky V, Sutera C, Tobias W A, Urciuoli G M, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zana L, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, Zhu P
Irfu, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France.
Faculté des sciences de Monastir, 5000 Tunisia.
Phys Rev Lett. 2016 Dec 23;117(26):262001. doi: 10.1103/PhysRevLett.117.262001.
We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2 GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q^{2} regime.
我们展示了在 (x_{B}=0.36) 以及从 (1.5) 到 (2\ GeV^{2}) 的三个不同 (Q^{2}) 值下深度虚光子产生 (\pi^{0}) 电产生截面的测量结果，这些结果来自杰斐逊实验室A厅的E07 - 007实验。采用罗森布鲁斯技术来分离纵向和横向响应。结果表明，截面主要由其横向分量主导，因此远离微扰量子色动力学预测的渐近极限。尽管如此，测量得到的干涉项 (\sigma_{LT}) 表明存在非零的纵向贡献。将结果与基于广义部分子分布（GPDs）的领先扭转方法的几个模型进行了比较。特别是，与那些散射振幅包括核子的手征奇（横动量分布）GPDs与扭转 - 3 介子分布振幅的卷积项的模型取得了较好的一致性。这个实验，连同之前广泛的未分离测量，为通过高 (Q^{2}) 区域的中性介子电产生来获取横动量分布GPDs这一令人兴奋的想法提供了有力支持。
