Eur. Phys. J. A (2008) 35: 299-305
https://doi.org/10.1140/epja/i2007-10558-3

Regular Article - Experimental Physics

Polarization in hyperon photo- and electro-production^⋆

Department of Physics, Carnegie Mellon University, 15213, Pittsburgh, PA, USA

^* e-mail: schumacher@cmu.edu

Received: 10 November 2007
Accepted: 21 January 2008
Published online: 21 March 2008

Abstract

Multiple polarization observables must be measured to access the amplitude structure of pseudoscalar meson photoproduction off the proton. The hyperon-producing reactions are especially attractive to study, since the weak decays allow straightforward measurement of the induced and recoil polarization observables. In this paper we emphasize γ + p → K ⁺ + Λ , discussing recent measurements of C_x, C_z, and P for this reaction. An empirical constraint on the helicity amplitudes is obtained. A simplified model involving spin-flip and spin-non-flip amplitudes is presented. Finally, a semi-classical model of how the polarization may arise is presented.