String model description of polarisation and angular distributions in ¯pp → ¯ΛΛ at low energies
Abstract:The observed polarisation of Λ hyperons from the inclusive pA → ΛX reaction at high energies has previously been well described within the Lund string model through polarised s¯s quark pair production in the string breaking hadronisation process. This model is here applied to the exclusive ¯pp → ¯ΛΛ reaction at low energies and compared to available data sets down to an incident-beam momentum of 1.835 GeV/c. This required an extension of the diquark scattering model to involve three components: an isotropic part relevant close to the threshold, a spectator part and a forward-scattering part as in pA → ΛX at high energies. The observed angular distributions are then reproduced and, for momentum transfers above | t'| = 0.2 GeV2, agreement with the measured polarisation is also obtained.