Photoproduction of Lambda(1405) and Sigma^{0}(1385) on the proton at E_\gamma = 1.5-2.4 GeV

TL;DR

This study measures the differential cross sections for photoproduction of Lambda(1405) and Sigma(1385) hyperons on the proton, revealing differences in decay line shapes and production ratios across photon energies, providing new insights into hyperon production mechanisms.

Contribution

First measurement of Lambda(1405) photoproduction cross section and analysis of decay line shapes, highlighting interference effects and energy-dependent production ratios.

Findings

Different decay line shapes for Lambda(1405) in two modes.

Decreasing ratio of Lambda(1405) to Sigma(1385) production with increasing photon energy.

Indications of different production mechanisms at various energies.

Abstract

Differential cross sections for $\gamma p \to K^+\Lambda(1405)$ and $\gamma p \to K^+\Sigma^0(1385)$ reactions have been measured in the photon energy range from 1.5 to 2.4 GeV and the angular range of $0.8<\cos(\Theta)<1.0$ for the $K^+$ scattering angle in the center-of-mass system. This data is the first measurement of the $\Lambda(1405)$ photoproduction cross section. The lineshapes of \LamS measured in $\Sigma^+\pi^-$ and $\Sigma^-\pi^+$ decay modes were different with each other, indicating a strong interference of the isospin 0 and 1 terms of the $\Sigma\pi$ scattering amplitudes. The ratios of \LamS production to \SigS production were measured in two photon energy ranges: near the production threshold ($1.5<E_\gamma<2.0$ GeV) and far from it ($2.0 <E_\gamma<2.4$ GeV). The observed ratio decreased in the higher photon energy region, which may suggest different production mechanisms and internal structures for these hyperon resonances.