Measurement of beam-recoil observables Ox, Oz and target asymmetry for the reaction gamma p -> K Lambda

TL;DR

This paper reports measurements of beam-recoil observables Ox and Oz, and target asymmetry T, for the gamma p -> K Lambda reaction, providing data to refine models of nucleon resonances around 1900 MeV.

Contribution

First measurements of Ox, Oz, and T for this reaction over a wide energy range, informing resonance models.

Findings

Data supports the inclusion of new or poorly known resonances near 1900 MeV.

Results align with isobar models requiring additional resonances.

Provides new polarization data for hyperon photoproduction.

Abstract

The double polarization (beam-recoil) observables Ox and Oz have been measured for the reaction gamma p -> K Lambda from threshold production to Egamma = 1500 MeV. The data were obtained with the linearly polarized beam of the GRAAL facility. Values for the target asymmetry T could also be extracted despite the use of an unpolarized target. Analyses of our results by two isobar models tend to confirm the necessity to include new or poorly known resonances in the 1900 MeV mass region.