Measurement of Beam-Recoil Observables $C_x$ and $C_z$ for $K^+\Lambda$ Photoproduction

TL;DR

This paper reports extended measurements of polarization observables $C_x$ and $C_z$ in $K^+\Lambda$ photoproduction, covering higher energies with improved precision to better constrain nucleon resonance models.

Contribution

It extends previous CLAS measurements of $C_x$ and $C_z$ to higher energies up to $W=3.33$ GeV with improved statistical accuracy.

Findings

Extended the kinematic range of polarization measurements.

Provided tighter constraints on reaction models.

Improved understanding of resonance and t-channel contributions.

Abstract

Exclusive photoproduction of $K^+ \Lambda$ final states off a proton target has been an important component in the search for missing nucleon resonances and our understanding of the production of final states containing strange quarks. Polarization observables have been instrumental in this effort. The current work is an extension of previously published CLAS results on the beam-recoil transferred polarization observables $C_x$ and $C_z$. We extend the kinematic range up to invariant mass $W=3.33$~GeV from the previous limit of $W=2.5$~GeV with significantly improved statistical precision in the region of overlap. These data will provide for tighter constraints on the reaction models used to unravel the spectrum of nucleon resonances and their properties by not only improving the statistical precision of the data within the resonance region, but also by constraining $t$-channel processes that dominate at higher $W$ but extend into the resonance region.