Overview of the electromagnetic production of strange mesons at MAMI

The Mainz Microtron MAMI provides a continuous-wave unpolarized or spin-polarized electron beam with energies up to 1.6 GeV and high degrees of polarization. Electro-production of strange mesons is performed in the multi-spectrometer facility with the Kaos spectrometer for kaon detection and a high-resolution spectrometer for electron detection in plane or out of plane. Differential cross section measurements of exclusive p(e, ^{e 'K +})Λ, ^σ0 reactions at low four-momentum transfers in the nucleon's third resonance region have been done, followed by a measurement of the beam helicity asymmetry for p(e→,e'K+)Λ. These studies are important for the understanding of the effective coupling of photons to the hadrons and their resonances and electromagnetic form factors entering different effective Lagrangian models for photo- and electro-production of strangeness. The polarized structure function, extracted from the beam helicity asymmetry, shows an especially high sensitivity to model parameters.