Observation of a cross-section enhancement near mass threshold in $e^{+}e^{-}\rightarrow\Lambda\bar{\Lambda}$
High Energy Physics - Experiment
2020-03-12 v4
Abstract
The process is studied using data samples at , 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at =2.2324 GeV, which is 1.0 MeV above the mass threshold, to be pb, where the first uncertainty is statistical and the second systematic. The substantial cross section near threshold is significantly larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at =2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with improved precision. Finally, the corresponding effective electromagnetic form factors of are deduced.
Keywords
Cite
@article{arxiv.1709.10236,
title = {Observation of a cross-section enhancement near mass threshold in $e^{+}e^{-}\rightarrow\Lambda\bar{\Lambda}$},
author = {M. Ablikim and M. N. Achasov and S. Ahmed and X. C. Ai and O. Albayrak and M. Albrecht and D. J. Ambrose and A. Amoroso and F. F. An and Q. An and J. Z. Bai and O. Bakina and R. Baldini Ferroli and Y. Ban and D. W. Bennett and J. V. Bennett and N. Berger and M. Bertani and D. Bettoni and J. M. Bian and F. Bianchi and E. Boger and I. Boyko and R. A. Briere and H. Cai and X. Cai and O. Cakir and A. Calcaterra and G. F. Cao and S. A. Cetin and J. Chai and J. F. Chang and G. Chelkov and G. Chen and H. S. Chen and J. C. Chen and M. L. Chen and S. Chen and S. J. Chen and X. Chen and X. R. Chen and Y. B. Chen and X. K. Chu and G. Cibinetto and H. L. Dai and J. P. Dai and A. Dbeyssi and D. Dedovich and Z. Y. Deng and A. Denig and I. Denysenko and M. Destefanis and F. DeMori and Y. Ding and C. Dong and J. Dong and L. Y. Dong and M. Y. Dong and Z. L. Dou and S. X. Du and P. F. Duan and J. Z. Fan and J. Fang and S. S. Fang and X. Fang and Y. Fang and R. Farinelli and L. Fava and S. Fegan and F. Feldbauer and G. Felici and C. Q. Feng and E. Fioravanti and M. Fritsch and C. D. Fu and Q. Gao and X. L. Gao and Y. Gao and Z. Gao and I. Garzia and K. Goetzen and L. Gong and W. X. Gong and W. Gradl and M. Greco and M. H. Gu and Y. T. Gu and Y. H. Guan and A. Q. Guo and L. B. Guo and R. P. Guo and Y. Guo and Y. P. Guo and Z. Haddadi and A. Hafner and S. Han and X. Q. Hao and F. A. Harris and K. L. He and F. H. Heinsius and T. Held and Y. K. Heng and T. Holtmann and Z. L. Hou and C. Hu and H. M. Hu and T. Hu and Y. Hu and G. S. Huang and J. S. Huang and X. T. Huang and X. Z. Huang and Z. L. Huang and T. Hussain and W. Ikegami Andersson and Q. Ji and Q. P. Ji and X. B. Ji and X. L. Ji and L. W. Jiang and X. S. Jiang and X. Y. Jiang and J. B. Jiao and Z. Jiao and D. P. Jin and S. Jin and T. Johansson and A. Julin and N. Kalantar-Nayestanaki and X. L. Kang and X. S. Kang and M. Kavatsyuk and B. C. Ke and P. Kiese and R. Kliemt and B. Kloss and O. B. Kolcu and B. Kopf and M. Kornicer and A. Kupsc and W. Kühn and J. S. Lange and M. Lara and P. Larin and H. Leithoff and C. Leng and C. Li and Cheng Li and D. M. Li and F. Li and F. Y. Li and G. Li and H. B. Li and H. J. Li and J. C. Li and Jin Li and K. Li and K. Li and Lei Li and P. L. Li and P. R. Li and Q. Y. Li and T. Li and W. D. Li and W. G. Li and X. L. Li and X. N. Li and X. Q. Li and Y. B. Li and Z. B. Li and H. Liang and Y. F. Liang and Y. T. Liang and G. R. Liao and D. X. Lin and B. Liu and B. J. Liu and C. X. Liu and D. Liu and F. H. Liu and Fang Liu and Feng Liu and H. B. Liu and H. H. Liu and H. H. Liu and H. M. Liu and J. Liu and J. B. Liu and J. P. Liu and J. Y. Liu and K. Liu and K. Y. Liu and L. D. Liu and P. L. Liu and Q. Liu and S. B. Liu and X. Liu and Y. B. Liu and Y. Y. Liu and Z. A. Liu and Zhiqing Liu and H. Loehner and Y. F. Long and X. C. Lou and H. J. Lu and J. G. Lu and Y. Lu and Y. P. Lu and C. L. Luo and M. X. Luo and T. Luo and X. L. Luo and X. R. Lyu and F. C. Ma and H. L. Ma and L. L. Ma and M. M. Ma and Q. M. Ma and T. Ma and X. N. Ma and X. Y. Ma and Y. M. Ma and F. E. Maas and M. Maggiora and Q. A. Malik and Y. J. Mao and Z. P. Mao and S. Marcello and J. G. Messchendorp and G. Mezzadri and J. Min and T. J. Min and R. E. Mitchell and X. H. Mo and Y. J. Mo and C. Morales Morales and G. Morello and N. Yu. Muchnoi and H. Muramatsu and P. Musiol and Y. Nefedov and F. Nerling and I. B. Nikolaev and Z. Ning and S. Nisar and S. L. Niu and X. Y. Niu and S. L. Olsen and Q. Ouyang and S. Pacetti and Y. Pan and M. Papenbrock and P. Patteri and M. Pelizaeus and H. P. Peng and K. Peters and J. Pettersson and J. L. Ping and R. G. Ping and R. Poling and V. Prasad and H. R. Qi and M. Qi and S. Qian and C. F. Qiao and L. Q. Qin and N. Qin and X. S. Qin and Z. H. Qin and J. F. Qiu and K. H. Rashid and C. F. Redmer and M. Ripka and G. Rong and Ch. Rosner and X. D. Ruan and A. Sarantsev and M. Savrié and C. Schnier and K. Schoenning and W. Shan and M. Shao and C. P. Shen and P. X. Shen and X. Y. Shen and H. Y. Sheng and W. M. Song and X. Y. Song and S. Sosio and S. Spataro and G. X. Sun and J. F. Sun and S. S. Sun and X. H. Sun and Y. J. Sun and Y. Z. Sun and Z. J. Sun and Z. T. Sun and C. J. Tang and X. Tang and I. Tapan and E. H. Thorndike and M. Tiemens and I. Uman and G. S. Varner and B. Wang and B. L. Wang and D. Wang and D. Y. Wang and K. Wang and L. L. Wang and L. S. Wang and M. Wang and P. Wang and P. L. Wang and W. Wang and W. P. Wang and X. F. Wang and Y. Wang and Y. D. Wang and Y. F. Wang and Y. Q. Wang and Z. Wang and Z. G. Wang and Z. H. Wang and Z. Y. Wang and Zongyuan Wang and T. Weber and D. H. Wei and P. Weidenkaff and S. P. Wen and U. Wiedner and M. Wolke and L. H. Wu and L. J. Wu and Z. Wu and L. Xia and L. G. Xia and Y. Xia and D. Xiao and H. Xiao and Z. J. Xiao and Y. G. Xie and Y. H. Xie and Q. L. Xiu and G. F. Xu and J. J. Xu and L. Xu and Q. J. Xu and Q. N. Xu and X. P. Xu and L. Yan and W. B. Yan and W. C. Yan and Y. H. Yan and H. J. Yang and H. X. Yang and L. Yang and Y. X. Yang and M. Ye and M. H. Ye and J. H. Yin and Z. Y. You and B. X. Yu and C. X. Yu and J. S. Yu and C. Z. Yuan and Y. Yuan and A. Yuncu and A. A. Zafar and Y. Zeng and Z. Zeng and B. X. Zhang and B. Y. Zhang and C. C. Zhang and D. H. Zhang and H. H. Zhang and H. Y. Zhang and J. Zhang and J. J. Zhang and J. L. Zhang and J. Q. Zhang and J. W. Zhang and J. Y. Zhang and J. Z. Zhang and K. Zhang and L. Zhang and S. Q. Zhang and X. Y. Zhang and Y. Zhang and Y. Zhang and Y. H. Zhang and Y. N. Zhang and Y. T. Zhang and Yu Zhang and Z. H. Zhang and Z. P. Zhang and Z. Y. Zhang and G. Zhao and J. W. Zhao and J. Y. Zhao and J. Z. Zhao and Lei Zhao and Ling Zhao and M. G. Zhao and Q. Zhao and Q. W. Zhao and S. J. Zhao and T. C. Zhao and Y. B. Zhao and Z. G. Zhao and A. Zhemchugov and B. Zheng and J. P. Zheng and W. J. Zheng and Y. H. Zheng and B. Zhong and L. Zhou and X. Zhou and X. K. Zhou and X. R. Zhou and X. Y. Zhou and K. Zhu and K. J. Zhu and S. Zhu and S. H. Zhu and X. L. Zhu and Y. C. Zhu and Y. S. Zhu and Z. A. Zhu and J. Zhuang and L. Zotti and B. S. Zou and J. H. Zou},
journal= {arXiv preprint arXiv:1709.10236},
year = {2020}
}