First results for 16 0(TT *, TT ± p) 15 N g . s . at 240 MeV for 0 n = 35°, 60°, and 130° in quasifree kinematics are reported. TT + /7T~ cross-section ratios much greater than for scattering by free protons are interpreted as due to a A-TV interaction interfering with the quasifree process.
The vector analyzing power (iT n ) in elastic n-d^i scattering has been measured for several angles at T^ = 142 and 256 MeV. The results are compared with calculations reported in the literature. At the lower energies, Faddeev calculations agree fairly well with the data. At the higher energies, the experimental results differ markedly from any conventional calculation, but agree surprisingly well with predictions in which effects of dibaryon resonances are explicitly included. PACS numbers: 25.80.+ f, 25.10.+ S, 21.30.+ y, 13.75.CsThe two-nueleon system-the possibility of resonances in this system in particular-has recently been the subject of intense investigation. The measurement oip-p total cross sections with both polarized proton beams and targets was the first experiment which showed some hint of possible dibaryon resonances. 1 Several phase-shift analyses 2 and a dispersion-relation analysis 3 have been made of these data in which the possible existence of dibaryons was investigated but the conclusions have remained controversial. 4 An anomalous structure in the proton polarization from deuteron photodisintegration has also been reported 5 but the detailed assignment of dibaryon quantum numbers to explain these anomalies remains less than conclusive. A measurement of Ao L (pd) recently gave evidence for structure in the isospin-0 channel. 6 Since these suspected dibaryon resonances in the p-p channel have large inelasticities, there must be a considerable coupling into the u-d and n-np channels. The ir-d channel is particularly useful since it is the only channel where at pres-ent the "background" amplitude can be calculated with sufficient confidence to study the effects of dibaryon resonance admixtures. The differential cross sections for the elastic Tr + -d scattering at intermediate energies have been measured very precisely by Gabathuler etal. 7 A remarkable feature of these cross-section data is the deep minimum in the angular distribution at 256 MeV incident pion energy, which so far has not been reproduced by even the most sophisticated Faddeev calculations 8 " 10 which include all 5 and P pionnucleon partial waves, the effect of intermediate 7r absorption, and a realistic deuteron wave function. Therefore, it is suspected that some essential ingredient in the ir-d reaction dynamics is still missing. A phase-shift analysis of the 7r + -d cross sections 11 showed counterclockwise Argand loops for J 7r = 2 + and 3" amplitudes at energies corresponding to possible 1 D 2 and S F 3 dibaryons but in this analysis there exists no possibility to separate the effects of A-N interactions from real resonances. Kanai etal. 12 have proposed that the deficiencies in reproducing the large-angle 167
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