Constraints on the spin-averaged Λp scattering length and effective
range have been obtained from measurements of the pp→pK+Λ reaction
close to the production threshold by comparing model phase-space Dalitz plot
occupations with experimental ones. The data fix well the position of the
virtual bound state in the Λp system. Combining this with information
from elastic Λp scattering measurements at slightly higher energies,
together with the fact that the hyperdeuteron is not bound, leads to a new
determination of the low energy Λp scattering parameters.Comment: 18 pages, 7 figure