1D2 Proton-Proton Reaction in Sub-GeV Region and the Possible Existence of a Diproton Resonance

Abstract

'D, proton-proton reactions in sub-GeV region are investigated by means of a multichannel N/D formalism with complex anomalous singularities. The singularities are ascertained to play an important role in the inelastic reactions. The solution predicts that the real phase shift has a bump at 600 MeV and an associated broad dip and that a diproton resonance exists. § I. Introduction Proton-proton scattering data obtained hitherto are believed to be reasonably complete and accurate in the elastic energy region, and the phase shifts have been determined fairly precisely_D-sJ In- the inelastic energy region above 280 MeV, extensive elastic scattering data sets exist only at three narrow energy bands centered at 330, 425 and 640 MeV. At 425 and 640 MeV where the imaginary phase shifts are not negligible, the data sets are not so complete as the lower energy data sets. Moreover, the inelastic data to be analyzed together with the elastic data are very meager. In these situations, for all the attempts by some authors,4' we have not had a reliably accurate and unique solution of the phase shift analysis in the inelastic energy region above 425 MeV_ However, it is very significant to determine phase shifts in the sub-Ge V region. If we get a reliable . phase shift solution, we can investigate, for example, the applicability of the one-boson exchange model5' (OBE model) including inelastic processes in the high-energy region. Some coupling parameters may be possibly changed considerably due to absorption effects. If the OBE model is applicable, probably with some modification, then we will be able to investigate more realis­ tically relations between the OBE model and the dual resonance model, the Regge polology and the other models. of highenergy two-body reactions. It is especially interesting and significant to investigate the p-p, 1D 2 state in the sub-Ge V region from two reasons.· The one is that the absorption in the state is known to be very large from kinematical considerations and from the differential cross section data of p + P~n: +D. The other reason is concerned with the possible existence of a resonance in this state. The possibility was first inve­ stigated by Arndt 6 ' ·from a point of view aimed at a similarity of singularity struc­ ture between the P-P, 1D 2 and the n:-D, D 13 scattering amplitudes. He used Nj D