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A potential model of the Λ−N interaction containing short-range repulsions is constructed to study charge-symmetry-breaking (CSB). Rank-2 nonlocal central potentials and a rank-1 approximation to them (referred to as UPAA) are required to fit low-energy Λ−p scattering cross sections, the Λ-separation energy (BΛ) from ΛH3, and a dimensionless parameter which partially characterizes the CSB part of the binding-energy difference between ΛH4 and ΛH4. In a scan of these data, a class of potentials with acceptable x2 fits is found. Repulsions are seen to reduce significantly the lower limits of the singlet and triplet CSB strengths required in the entire data scan, from the CSB found earlier without including repulsions. In particular, for the largest value of BΛ used, 0.25 MeV, qualitative agreement with Downs's SU3 model of CSB is attained, in that the Λ−p CSB singlet interaction can be repulsive. This conclusion also holds for the UPAA, with an indication that a short-range weakening of Λ−N attraction has an effect similar to a Λ−N repulsion. Effects of isospin mixing in ΛH3 are taken into account. The Λ−N potentials resulting from this analysis are seen to vary in a systematic way within the statistical spread of available data.

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©1971 The American Physical Society