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Differential Cross Section of the pn ! pp͑ ͑ ͑ 1 S 0 ͒ ͒ ͒p 2 Reaction Extracted from pd ! pppp 2The double differential cross section for pn ! pp͑ 1 S 0 ͒p 2 at three beam energies has been extracted from the quasifree process pd ! pppp 2 . A comparison is carried out with single differential cross section measurements for 3 He͑p 2 , pn͒n, where the pion is thought to be absorbed onto a pp͑ 1 S 0 ͒ "diproton" state. A significant difference is observed in the shape of the angular distribution between the production and absorption data. This difference is ascribed to the effects of the 3 He nuclear environment characterizing the absorption process; however, an adequate theoretical explanation is not available. [S0031-9007 (98)06103-1]

We report the observation of a large asymmetry in the elastic scattering of 100 MeV TT^ from a polarized ^He target. Measurements have been made at laboratory angles of 60°, 80°, and 100°, with the largest value /4» =0.89 ±0.12 occurring at 80°, near a cross-section minimum. This asymmetry is the largest observed to date in pion scattering from a spin-j nucleus. The Ay data are qualitatively reproduced by a schematic model; however, agreement with the data is significantly improved when realistic three-body Faddeev wave functions and a full nonlocal distorted-wave impulse approximation reaction model are used.

A search was conducted for a light baryon X " in the mass range MN + M , _> Mx 1 M N , by bombarding a CH2 target with 460 MeV protons, and detecting the products in the Medium Resolution Spectrometer, which was placed at a scattering angle of 15 degrees. No doubly charged baryon in this mass range was detected, thus setting an upper limit of a few tens pb/sr for the reaction. The experiment indicates that if such a light baryon exists its interaction with the "ordinary" physical world is very weak, probably at least 10' times weaker than the strong interaction.PACS number(s): 13.75.-n, 13.30. -a, 25.40. -h