Hyperon Photo- and Electro- Production Experiments at CLAS

Abstract

Developments in strangeness photo-and electro-production off the proton, as investigated using the CLAS system in Hall B at Jefferson Lab, are discussed in this paper. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the Λ(1405), which shows signs of being a composite meson-baryon object of mixed isospin. The work on other hyperons such as the Ξ resonances will be mentioned, and future prospects outlined.

DN interaction from meson exchange

“…This experiment is providing the first results on the Λ(1405) photoproduction analyzing all three πΣ decay modes. Preliminary results show differences in the Λ(1405) lineshapes as well as different Λ(1405) differential cross sections for each πΣ decay mode [49].…”

Electromagnetic production of hyperon resonances

“…Of special interest, as mentioned above, is the observation of new N * resonances using both cross sections and polarization data. Curiously, the Λ is polarized nearly 100% in the direction of circularly polarized photons [6] which was not predicted by any theoretical reaction model before the CLAS measurements. The precision of the CLAS data has sparked new theoretical interest in strangeness production.…”

“…Results for the reaction γ p → K + Λ measured at CLAS have been published [5] and are described elsewhere [6]. Of special interest, as mentioned above, is the observation of new N * resonances using both cross sections and polarization data.…”