Observation of a Near-Threshold Enhancement in the pp¯ Mass Spectrum from Radiative J/ψ→γpp¯ Decays

Bai, J. Z.; Ban, Y.; Bian, J. G.; Cai, X.; Chang, J. F.; Chen, H. F.; Chen, H. S.; Chen, J.; Chen, Jie; Chen, J. C.; Chen, Y. B.; P., S.; Chu, Y. P.; Cui, X. Z.; Dai, Yan; Dai, Y. S.; Liu, Dong; Du, S. X.; Du, Z. Z.; Dunwoodie, W.; Fang, J. M.; Fang, S. S.; Fu, C. D.; Fu, Hai-Bing; Fu, L. P.; Gao, C. S.; Gao, M.; Gao, Yang; Gong, Ming; Gong, W. X.; Gu, S.; Guo, Y. N.; Guo, Y. Q.; Guo, Z. J.; Han, S.; Harris, F. A.; He, J.; He, K. L.; He, M.; He, Xiaohu; Heng, Y. K.; Hong, Tao; Hu, H. M.; Hu, T.; Huang, G. S.; Huang, L. Q.; Huang, X. P.; Izen, J. M.; Ji, Xiang; Jiang, C. H.; Jiang, X. S.; Jin, D. P.; Jin, S.; Jin, Yanling; Jones, B. D.; Ke, Z. J.; Kong, D.; Lai, Y. F.; Li, F.; Li, G.; Li, H. H.; Li, J.; Li, J. C.; Li, K.; Li, Q. J.; Li, R. B.; Li, R. Y.; Li, W.; Li, W. G.; Li, X. Q.; Li, X. S.; Liu, C. F.; Liu, C. X.; Liu, Fang; Liu, F.; Liu, H. M.; Liu, J. B.; Liu, J. P.; Liu, R. G.; Liu, Y.; Liu, Z. A.; Liu, Z. X.; Lou, X. C.; Lu, G. R.; Lu, F. X.; Lu, H.; Lü, J. G.; Lu, Z. J.; Luo, X. L.; C., E.; C., F.; Iso, J. M.; Malchow, R.; Mao, Z. P.; Meng, Xu-Dong; Mo, X. H.; Nie, J.; Nie, Z. D.; Olsen, S. L.; Paluselli, D.; Peng, H.; Qi, N. D.; Qian, C. D.; Qiu, Jie; Guo, Rong; Shen, D. L.; Shen, H. F.; Shen, X. Y.; Sheng, H. Y.; Shi, Feng; Song, L.; Sun, H. S.; Sun, S.; Sun, Yan; Sun, Zehua; Tang, S. Q.; Tang, X.; Tian, Dongxu; Tian, Yang; Toki, W. H.; Tong, G. L.; Varner, G.; Wang, J.; Wang, J. Z.; Wang, L.; Wang, L. S.; Wang, M.; Wang, Meng; Wang, P.; Wang, P. L.; Wang, W. F.; Wang, Y. F.; Wang, Zhe; Wang, Z.; Wang, Zheng; Wang, Z. Y.; Wei, C.; Wu, N.; Xia, X. M.; Xie, X. X.; Xu, G. F.; Xu, Y.; Xue, S.; Yan, Mi; Yan, W. B.; Yang, G. A.; Yang, H. X.; Yang, Jing; Yang, S.; Ye, M. H.; Ye, Y. X.; Ying, J.; Chen, Yu; Yu, G.; Yuan, C. Z.; Yuan, J. M.; Yuan, Y.; Yue, Qing; Zang, S. L.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. M.; Zhang, J. W.; Zhang, L. S.; Zhang, Q. J.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y. J.; Zhang, Yiyun; Zhang, Y. Y.; Zhang, Z. P.; Zhao, Dongxu; Zhao, J. Z.; Zhao, Jiawei; Zhao, P. P.; Zhao, W. R.; Zhao, Y.; Zhao, Z. G.; Zheng, J. P.; Zheng, Lei; Zheng, Z. P.; Zhong, X. C.; Zhou, Bang-Rong; Zhou, G. M.; Zhou, Lina; Zhou, Na; Zhu, K.; Zhu, Q. M.; Zhu, Y. M.; Zhu, Yucan; Zhu, Yongfeng; Zhu, Z. A.; Zhuang, B. A.; Zou, B. S.

doi:10.1142/9789811217739_0028

Cited by 4 publications

(13 citation statements)

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“…[15]. A related strong enhancement of the absorption is observed in the light antiprotonic atoms.The comparison of atomic level widths in a series of atoms (H, 2 H, 3 H, 3 He, 4 He) allows to test the absorption of antiprotons on more and more strongly bound protons up to subthreshold energies of E pp down to − 40 MeV [3]. The enhancement of absorption below the pp threshold is consistent with both results from Refs.…”

Section: Introductionsupporting

confidence: 86%

“…Beyond, a depression at low pp energies is seen in the data. These two reactions indicate a strong P -wave dominance in reaction (3) and a sizable P wave in reaction (4). Both find a natural explanation in the model developed in the present work.…”

Section: Introductionsupporting

confidence: 65%

“…The effect of infrared enhancement should be seen in the experimental data as a peak at the end of the spectrum, that is, in the soft photon limit. However, it is also clear [4,5] that contributions from the infrared photons (k < 50 MeV/c) have been effectively cut out from the data. We refer the reader to the discussion at the end of Section V A.…”

Section: A the Initial N N Statementioning

confidence: 99%

“…displays no near threshold enhancement [4]. Recent BES III experiments [17,18] have extended these measurements to the reaction…”

Section: Introductionmentioning

confidence: 97%

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Photon or meson formation in J/ψ decays into pp¯

2018

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The measurements of the J/ψ → γpp decays by the BES Collaboration indicate an enhancement at the pp threshold which, however, is not present in the J/ψ decays into ωpp and into πpp. Here, two processes for describing the decays J/ψ → Bpp where B = γ, ω are presented in some detail and the cases B = φ, π are briefly touched on. The first one, applied not only to the radiative decay to reproduce the threshold peak but also to the ωpp decay channel to improve the description of the spectrum, postulates a direct emission of the boson before the baryon pair is formed. The second process assumes that the boson B is emitted from the baryon pair following the J/ψ decay and includes for the decays into γpp a final state nucleon-antinucleon interaction based on the Paris N N potential. The reproduction of the pp distribution in the J/ψ → ωpp decays needs a final state interaction involving a N (2050) 3/2 − resonance. The photon-and meson-emission rates are reproduced in a semi-quantitative way. PACS numbers: 12.39.Pn, 13.20Gd, 13.60.le, 13.75.Cs, 14.65Dw an enhancement close to the pp threshold has been observed by the BES 1 Collaboration [4,5]. We note that both the J/ψ and the photon have J P C = 1 −− . There are three final pp states allowed by parity, P , and charge-conjugation, 1 Beijing Electron Sprectrometer

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Section: Introductionsupporting

confidence: 86%

Section: Introductionsupporting

confidence: 65%

Section: A the Initial N N Statementioning

confidence: 99%

“…displays no near threshold enhancement [4]. Recent BES III experiments [17,18] have extended these measurements to the reaction…”

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Photon or meson formation in J/ψ decays into pp¯

2018

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“…In this way a resonant-like behavior was observed in the decay J/ψ → γpp. The experiment performed by the BES Collaboration [1] found an enhancement in the pp close to the threshold energy equal to 1876 MeV. With a model it was attributed to a sub-threshold peak at invariant mass of 1859 MeV.…”

Section: Introductionmentioning

confidence: 95%

Extraction of baryonia from the lightest anti-protonic atoms

Loiseau,

Wycech

2020

Preprint

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Anti-protonic hydrogen and helium atoms are analyzed. Level shifts and width are expressed in terms of p-nucleon sub-threshold scattering lengths and volumes. Experimental data are compared to results obtained from the 2009 version of the Paris N N interaction potential. Comparison with 1999 version is also made. Effects of N N quasi-bound states are discussed. Atomic 2P hyperfine structure is calculated for antiprotonic deuterium and the significance of new measurements is indicated.

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