Cross sections and Rosenbluth separations in 1H(e, e′ K+)Λ up to Q2=2.35 GeV2

The kaon electroproduction reaction H-1(e, e ' K+)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 GeV2, and the longitudinal, sigma(L), and transverse, 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 sigma(T) and sigma(L).