Low-Energy Lambda-P Scattering Parameters From The Pp -> Pk(+)Lambda Reaction

Constraints on the spin-averaged Lambda p scattering length and effective range have been obtained from measurements of the pp --> pK(+)Lambda 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 Lambda p system. Combining this with information from elastic Lambda p 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 Lambda p scattering parameters.