Baryonium, a common ground for atomic and high energy physics
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Baryonium, a common ground for atomic and high energy physics S. Wycech · J.-P. Dedonder · B. Loiseau
© The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract Indications of the existence of quasi-bound states in the N N system are presented. In their measurements, the BES collaboration has discoverd a broad enhancement close to the pp threshold in the S wave, isospin 0 state formed in radiative decays of J /ψ. Another enhancement located about 50 MeV below the threshold was found in mesonic decays of J /ψ. In terms of the Paris potential model it was shown that these are likely to represent the same state. Antiprotonic atomic data provide some support for this interpretation and indicate the existence of another fairly narrow quasi-bound state in a P wave. Keywords Baryonium · J/psi decays · antiprotonic atoms J /ψ
1 Introduction Nucleon-antinucleon quasi-bound states, or states coupled to these, were searched for in the days of LEAR at CERN. Nothing has been found, but broad states or states close to the threshold were not excluded. References [1], [2] indicate conclusions of a long series of measurements. In reference [1] a search for narrow signals in the γ spectrum from pp
Proceedings of the International Conference on Exotic Atoms and Related Topics (EXA 2014), Vienna, Austria, 15-19 September S. Wycech () Andrzej Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw, Poland e-mail: [email protected] J.-P. Dedonder · B. Loiseau ´ Laboratoire de Physique Nucl´eaire et de Hautes Energies, Sorbonne Universit´es, Universit´e Pierre et Marie Curie, Sorbonne Paris Cit´e, Universit´e Paris Diderot and IN2P3-CNRS UMR 7585, 4 place Jussieu, 75252 Paris, France J.-P. Dedonder e-mail: [email protected] B. Loiseau e-mail: [email protected]
S. Wycech et al. Table 1 Low energy pp states allowed in the J /ψ → γpp decays. The first column gives decay modes and specifies the internal states of pp pair. For both photon and J /ψ the J P C = 1(−−) . The second column gives J P C for the pp system Decay mode
J P C (pp)
γpp(1 S0 )
0−+
γpp(3 P0 )
0++
γpp(3 P
1++
1)
Table 2 Decay modes and the pp states allowed in the J /ψ → boson pp decays Decay mode
Branching
pp states allowed
γpp
3.8(±1.0) · 10−4 [8]
ωpp
1.1(±0.15) · 10−3 [9]
π 0 pp
1.19(±.08) · 10−3 [8]
pp
2.12(±0.1) · 10−3 [8]
1 S ,3 P ,3 P 0 1 0 11 S ,13 P ,13 P 0 1 0 33 S ,31 P 1 1 13 S 1
annihilation at rest was performed and no discoveries were found in the region below 1770 MeV and < 25 MeV. Another experiment looking for missing mass in the reactions pp → π − X and pd → pX brought similar conclusions. On the experimental side, one possible reason for the failure is the large background due to annihilation processes. Another is the large number of allowed partial waves. On the theory side, it was assumed that the annihilation reaction involve ∼ 2Mp mass transfer and by the uncertainty principle it has to be very short ranged. It was thus expected that widths of quasi-bound states m
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