Photoproduction of the $\Lambda$(1405) Hyperon

TL;DR

This paper proposes a new experimental measurement of the $ ext{Lambda}(1405)$ hyperon via photoproduction at A2, aiming to clarify its controversial nature and provide data for theoretical models, including decay channels and polarization observables.

Contribution

It introduces a novel, high-precision measurement of the $ ext{Lambda}(1405)$ production and decay, including the first measurement of its radiative decays and the unmeasured beam-helicity observable.

Findings

Enhanced understanding of $ ext{Lambda}(1405)$ production mechanisms.

First measurement of its radiative decay channels.

Improved constraints for theoretical models like chiral perturbation theory.

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 $\gamma p\rightarrow K^+\Lambda(1405)$. 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.