/ 95 07 40 3 v 1 2 5 Ju l 1 99 5 The strange quark spin of the proton in semi - inclusive Λ leptoproduction ∗

Considering the possible interpretation of the Ellis-Jaffe sum rule violation that the strange quark in the polarized proton is remarkably polarized in the opposite direction of the proton spin, we investigate its implication in the semi-inclusive Λ production in deep inelastic process with the electron beam unpolarized and proton target polarized longitudinally. As a result, we find that the measurement of the Λ polarization in the process considered can provide clean information about the strange quark spin distribution in the proton.