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 $\gamma \overrightarrow{p}{K}^{+}\Lambda ,$ for $E_{\gamma }^{\mathrm{lab}}<~$2.5 GeV, $e\overrightarrow{p}{e}^{\prime }{K}^{+}\Lambda ,$ as well as the branching ratio for the crossed channel reaction $K^{-}\overrightarrow{p}\gamma \Lambda ,$ with stopped kaons. The sensitivity, from moderate to significant, of various observables to such effects are discussed.

• Received 1 December 1997

DOI:https://doi.org/10.1103/PhysRevC.58.75