Strange-baryon production via charge-changing weak currents in high-energy electron-capture reactions.

Abstract

We investigate strange-baryon \ensuremath{\Lambda} and ${\ensuremath{\Sigma}}^{0}$ production via charge-changing weak currents on a proton target induced by high-energy electrons. To evaluate the various weak form factors, including vector, weak-magnetism, and scalar form factors for the polar-vector current and the axial-vector, pseudoscalar, and weak electric form factors for the axial-vector current, we adopt the flavor-SU(6) wave functions with quarks described as confining Dirac particles. The quark wave function adopted is of the form given by the MIT bag model, with or without the sharp surface smoothed out. In the few-GeV range, it is found that the cross section for large-angle \ensuremath{\Lambda} production is in the range of ${10}^{\mathrm{\ensuremath{-}}40}$ ${\mathrm{cm}}^{2}$ while that for ${\ensuremath{\Sigma}}^{0}$ is smaller by about an order of magnitude. The cross section is sensitive to contributions due to vector, weak-magnetism, and axial-vector form factors. Measurements of these form factors in the few-GeV range provide tests of quark models for nucleons and strange baryons. Some important aspects, such as recoil effects, are briefly discussed.