Further measurement of proton polarization in deuteron photodisintegration at photon energies between 400 and 650 MeV: Possible evidence for dibaryon resonances

On the history of dibaryons and their final observation

“…In fact, such an effect has already been looked for previously by Kamae et al in corresponding data from the Tokyo electron synchrotron [129,130,131,132]. In order to describe the observed large polarizations in the region of d * (2380), they fitted a number of resonances to the data, among others also a J P = 3 + state.…”

“…Actually groups at Tokyo had been quite close already as early as 1977 considering measurements of the proton polarization in deuteron photodisintegration γd → pn [129,130,131,132]. They observed a strong increase of the polarization at energies beyond √ s = 2.2 GeV, reaching a maximum around 2.38 GeV and decreasing thereafter.…”

“…Only, their data favored a broad resonance of about 160 MeV width. Follow-up measurements and their analysis showed that the data and their analysis are best described by the assumption of several broad resonances of different spin-parity with widths larger than 200 MeV [132]. From the large widths it looks that these findings correspond to t-channel ∆∆ excitations rather than the narrow d * (2380) dibaryon resonance.…”

“…It was suggested that this behavior could be due to the excitation of a dibaryon resonance with a mass of 2380 MeV and preferably with quantum numbers I(J P ) = 0(3 + ) as predicted in 1964 by Dyson and Xuong [33] and -in close connection with the Bremsstrahlung measurements -by Kamae and Fujita [99] based on a non-relativistic one-boson exchange potential model. Subsequent measurements improving the data base allowed for resonance fitting, which led to the assignment of several broad resonances with widths of 200 MeV and beyond [130,131,132].…”

Deuteron photodisintegration by polarized photons in the region of the d⁎(2380)

“…In Ref. [34], it is claimed that the strongest d * (2380) effect should be seen in the a 6 coefficient. Some weak structure exhibiting a mass and width compatible with the established properties of the d * (2380) is evident in the a 6 coefficient.…”