Cross sections and Rosenbluth separations in {sup 1}H(e,e{sup '}K{sup +})LAMBDA up to Q{sup 2}=2.35 GeV{sup 2}

The kaon electroproduction reaction $^{1}\mathrm{H}$($e,{e}^{\ensuremath{'}}{K}^{+}$)$\ensuremath{\Lambda}$ was studied as a function of the virtual-photon four-momentum, ${Q}^{2}$, total energy, $W$, and momentum transfer, $t$, for different values of the virtual-photon polarization parameter. Data were taken at electron beam energies ranging from $3.40$ to $5.75$ GeV. The center of mass cross section was determined for twenty-one kinematics corresponding to ${Q}^{2}$ of $1.90$ and $2.35$ GeV${}^{2},$ and the longitudinal, ${\ensuremath{\sigma}}_{L}$, and transverse, ${\ensuremath{\sigma}}_{T}$, cross sections were separated using the Rosenbluth technique at fixed $W$ and $t$. The separated cross sections reveal a flat energy dependence at forward kaon angles not satisfactorily described by existing electroproduction models. Influence of the kaon pole on the cross sections was investigated by adopting an off-shell form factor in the Regge model, which better describes the observed energy dependence of ${\ensuremath{\sigma}}_{T}$ and ${\ensuremath{\sigma}}_{L}$.