Induced polarization ofΛ(1116)in kaon electroproduction

Abstract

We have measured the induced polarization of the Λ(1116) in the reaction ep → e K + Λ, detecting the scattered e and K + in the final state along with the proton from the decay Λ → pπ − . The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy W (1.6 ≤ W ≤ 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.

Coupled-channel analysis of pion- and eta-electroproduction with the Jülich-Bonn-Washington model

“…As a first step, the number of included partialwaves and the energy limits will be increased. Once completed, we will attempt an expansion to kaon electroproduction [8,[173][174][175][176][177][178], in the near-threshold region. We will also be in a position to explore resonance behavior at the pole as a function of Q the computing time granted through JARA on the super-computer JURECA [180] at Forschungszentrum Jülich that was used to produce the input at the photon point.…”