Abstract
Background: Measurements of polarization observables for the reactions $\vec{\gamma} p \rightarrow K^+ \Lambda$ and $\vec{\gamma} p \rightarrow K^+ \Sigma^0$ have been performed. This is part of a programme of measurements designed to study the spectrum of baryon resonances. Purpose: The accurate measurement of several polarization observables provides tight constraints for phenomenological fits. Beam-recoil observables for the $\vec{\gamma} p \rightarrow K^+ \Sigma^0$ reaction have not been reported before now. Method: The measurements were carried out using linearly polarized photon beams and the CLAS detector at the Thomas Jefferson National Accelerator Facility. The energy range of the results is 1.71\,GeV $<W<$ 2.19\,GeV, with an angular range $-0.75 < \cos\theta^{\star}_K < +0.85$. Results: The observables extracted for both reactions are beam asymmetry $\Sigma$, target asymmetry $T$, and the beam-recoil double polarization observables $O_x$ and $O_z$. Conclusions: Comparison with theoretical fits indicates that in the regions where no previous data existed, the new data contain significant new information, and strengthen the evidence for the set of resonances used in the latest Bonn-Gatchina fit.
Highlights
A critical ingredient in the understanding of QCD in the nonperturbative regime is a detailed knowledge of the spectrum of hadrons
The observables extracted for both reactions are beam asymmetry, target asymmetry T, and the beam-recoil double polarization observables Ox and Oz
We report measurements of the observables, T, Ox, and Oz for the reactions γ p → K+ and γ p → K+ 0 in the energy range 1.71 < W < 2.19 GeV, and the angular range −0.75 < cos θK < +0.85,1 where θK is the center-of-mass kaon scattering angle
Summary
A critical ingredient in the understanding of QCD in the nonperturbative regime is a detailed knowledge of the spectrum of hadrons. Measurements of polarization observables for the reactions γ p → K+ and γ p → K+ 0 have been performed. This is part of a program of measurements designed to study the spectrum of baryon resonances in particular, and nonperturbative QCD in general. Results: The observables extracted for both reactions are beam asymmetry , target asymmetry T , and the beam-recoil double polarization observables Ox and Oz. Conclusions: Comparison with theoretical fits indicates that, in the regions where no previous data existed, the new data contain significant new information, and strengthen the evidence for the set of resonances used in the latest Bonn-Gatchina fit
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