Induced polarization of {\Lambda}(1116) in kaon electroproduction

TL;DR

This study measures the induced polarization of the Lambda(1116) hyperon in kaon electroproduction, revealing kinematic dependencies and Q^2 independence in a broad energy range, aiding the development of theoretical models and resonance searches.

Contribution

First measurement of Lambda(1116) induced polarization in kaon electroproduction over a wide kinematic range, providing crucial data for theoretical modeling and resonance identification.

Findings

Induced polarization varies with energy and angle.

Induced polarization is Q^2 independent within studied range.

Data suggest strong Q^2 dependence below measured values.

Abstract

We have measured the induced polarization of the ${\Lambda}(1116)$ in the reaction $ep\rightarrow e'K^+{\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\Lambda\rightarrow p\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\leq W \leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances.