Off-shell effects in the electromagnetic production of strangeness

Abstract

Previous approaches to the photoproduction and electroproduction of strangeness off the proton, based upon effective hadronic Lagrangians, are extended here to incorporate the so-called off-shell effects inherent to the fermions with spin $>~3/2.$ A formalism for intermediate-state, spin-3/2, nucleonic, and hyperonic resonances is presented and applied to the processes $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{p}{K}^{+}\ensuremath{\Lambda},$ for ${E}_{\ensuremath{\gamma}}^{\mathrm{lab}}<~$2.5 GeV, $e\stackrel{\ensuremath{\rightarrow}}{p}{e}^{\ensuremath{'}}{K}^{+}\ensuremath{\Lambda},$ as well as the branching ratio for the crossed channel reaction ${K}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\gamma}\ensuremath{\Lambda},$ with stopped kaons. The sensitivity, from moderate to significant, of various observables to such effects are discussed.