N*重子共振产生大质量虚光子发射的首次测量
核实验
2026-03-25 v4
摘要
利用GSI的高接受度双电子谱仪（HADES），以π介子束轰击CH靶，在 = 1.49 GeV的准自由反应 p n e+ e-中测量双电子（e+ e-）不变质量与角分布，获得了第二共振区重子类时电磁结构的首次信息。我们发现总截面 = 2.97 0.07data 0.21acc 0.31Zeff b。作为对包含双电子 inclusive 通道分析的补充，该数据集对重子类时跃迁的描述提供了关键检验。基于包含直接光子和矢量介子（）与重子耦合的矢量介子主导振幅的方法与数据吻合良好。在协变旁观者夸克模型中，通过电磁类时重子跃迁形状因子也获得了良好描述，表明介子云效应占主导。双电子角分布展现出具有纵向极化的虚光子（）贡献，这与实光子相反。虚光子角依赖性支持在n与n通道中均观测到的J=3/2、I=1/2贡献占主导。
引用
@article{arxiv.2205.15914,
title = {First measurement of massive virtual photon emission from N* baryon resonances},
author = {R. Abou Yassine and J. Adamczewski-Musch and O. Arnold and E. T. Atomssa and M. Becker and C. Behnke and J. C. Berger-Chen and A. Blanco and C. Blume and M. Böhmer and L. Chlad and P. Chudoba and I. Ciepał and S. Deb and C. Deveaux and D. Dittert and J. Dreyer and E. Epple and L. Fabbietti and P. Fonte and C. Franco and J. Friese and I. Fröhlich and J. Fortsch and T. Galatyuk and J. A. Garzón and R. Gernhäuser and R. Greifenhagen and M. Grunwald and M. Gumberidze and S. Harabasz and T. Heinz and T. Hennino and C. Höhne and F. Hojeij and R. Holzmann and M. Idzik and B. Kämpfer and K-H. Kampert and B. Kardan and V. Kedych and I. Koenig and W. Koenig and M. Kohls and J. Kolas and B. W. Kolb and G. Korcyl and G. Kornakov and R. Kotte and W. Krueger and A. Kugler and T. Kunz and R. Lalik and K. Lapidus and S. Linev and F. Linz and L. Lopes and M. Lorenz and T. Mahmoud and L. Maier and A. Malige and J. Markert and S. Maurus and V. Metag and J. Michel and D. M. Mihaylov and V. Mikhaylov and A. Molenda and C. Müntz and R. Münzer and M. Nabroth and L. Naumann and K. Nowakowski and J. Orliński and J. -H. Otto and Y. Parpottas and M. Parschau and C. Pauly and V. Pechenov and O. Pechenova and K. Piasecki and J. Pietraszko and T. Povar and K. Prościński and A. Prozorov and W. Przygoda and K. Pysz and B. Ramstein and N. Rathod and P. Rodriguez-Ramos and A. Rost and A. Rustamov and P. Salabura and T. Scheib and N. Schild and K. Schmidt-Sommerfeld and H. Schuldes and E. Schwab and F. Scozzi and F. Seck and P. Sellheim and J. Siebenson and L. Silva and U. Singh and J. Smyrski and S. Spataro and S. Spies and M. Stefaniak and H. Ströbele and J. Stroth and C. Sturm and K. Sumara and O. Svoboda and M. Szala and P. Tlusty and M. Traxler and H. Tsertos and I. C. Udrea and O. Vazquez-Doce and V. Wagner and A. A. Weber and C. Wendisch and M. G. Wiebusch and J. Wirth and A. Władyszewska and H. P. Zbroszczyk and E. Zherebtsova and M. Zieliński and P. Zumbruch and M. Zetenyi},
journal= {arXiv preprint arXiv:2205.15914},
year = {2026}
}
备注
revised version, 8 pages, 4 figures