Low-Energy $Λ-\p$ Scattering Parameters from the $pp \to pK^+Λ$ Reaction

Abstract

Constraints on the spin-averaged $Λp$ scattering length and effective range have been obtained from measurements of the $pp\to pK^+Λ$ 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.