Photoproduction of the $\Lambda$(1405) Hyperon

Abstract

We propose to use the high current photon beam available at A2 to produce the isosinglet $\Lambda (1405)1/2^{-}$ hyperon at threshold via $\gamma p\to K^{+}\Lambda (1405)$. Its nature is still controversial and actively debated. Since the only available photoproduction data from CLAS are lacking in precision in the ${\Sigma }^0{\pi }^0$ decay channel, we propose a new independent measurement of this most important pure $I=0$ final state including the unmeasured beam-helicity observable $I^{\odot }$. In addition, the excellent photon detection acceptance of the A2 setup will offer the opportunity for a first measurement of the radiative decays of the $\Lambda (1405)$, which will provide clean and stringent constraints for model descriptions in terms of, e.g., unitary chiral perturbation theory.

Proposal for an Experiment at MAMI, presented to the PAC 2016, November 2016, 32 pages, 25 figures