  We investigate the p(gamma,K+)Lambda and p(gamma,K+)Sigma^0 reactions within
a coupled-channels effective-Lagrangian method which is based on the K-matrix
approach. The two-body final channels included are pi-N, eta-N, phi-N, rho-N,
gamma-N, K-Lambda, and K-Sigma. Non-resonant meson-baryon interactions are
included in the model via nucleon intermediate states in the s- and u-channels
and meson exchanges in the t-channel amplitude and the u-channel resonances.
The nucleon resonances S11 (1535), S11 (1650), S31 (1620), P11 (1440), P11
(1710), P13 (1720), P33 (1232), P33 (1600), D13 (1520), D13 (1700), and D33
(1700) are included explicitly in the calculations. With a single parameter set
which was derived earlier from our analysis of the eta meson photoproduction,
the model describes well all the available cross section and polarization data
of the SAPHIR collaboration for the two investigated channels. The description
of the data of the CLAS collaboration, however, is not of the same quality. In
contrast to some previous studies, we do not find any compelling need for
including a D13 state with mass of around 2.0 GeV in order to reproduce the
data for the p(gamma,K+)Lambda reaction at photon energies corresponding to the
invariant mass around 1.9 GeV.
