Associated Lambda/Sigma electroproduction with the Kaos spectrometer at MAMI

Abstract

An instrument of central importance for the strangeness photo- and electroproduction at the 1.5-GeV electron beam of the MAMI accelerator at the Institut f\"ur Kernphysik in Mainz, Germany, is the newly installed magnetic spectrometer Kaos that is operated by the A1 collaboration in $(e,e'K)$ reactions on the proton or light nuclei. Its compact design and its capability to detect negative and positive charged particles simultaneously complements the existing spectrometers. The strangeness program performed with Kaos in 2008-9 is addressing some important issues in the field of elementary kaon photo- and electroproduction reactions. Although recent measurements have been performed at Jefferson Lab, there are still a number of open problems in the interpretation of the data and the description of the elementary process using phenomenological models. With the identification of $\Lambda$ and $\Sigma^0$ hyperons in the missing mass spectra from kaon production off a liquid hydrogen target it is demonstrated that the extended facility at MAMI is capable to perform strangeness electroproduction spectroscopy at low momentum transfers $Q^2$ < 0.5 (GeV/c)$^2$. The covered kinematics and systematic uncertainties in the cross-section extraction from the data are discussed.