Λ polarization in associated K+– Λ electro-production

Abstract

The result of a feasibility study to measure the Λ polarization in associated K +– Λ electro-production is presented. This measurement was performed in the experimental Hall C at Jefferson Lab. The scattered electron was detected in the HMS spectrometer, and the electro-produced kaon and the proton from the Λ→ pπ − decay were both detected in the SOS spectrometer. This quantity is very sensitive to the elementary p( e, e′ K) Λ process and gives information on resonance production, and Regge exchange, among others. The result presented was measured at Q 2=1.50 (GeV/c) 2 and cos θ Kγ CM=14°. The limits of the Λ polarization, with respect to the p γ× p K axis, were found to be −0.21 and +0.89 with a confidence level of 68%. The result is compared to theoretical predictions based on an effective hadronic field Lagrangian model and a Regge framework model.