Hypernuclear photoproduction

Abstract

The nuclear ( γ, K +) reaction is studied using a distorted wave impulse approximation including the full Coulomb plus kaon-nucleus interaction. The need to include kaon-hypernucleus interaction effects, especially at higher energies, is demonstrated. The sensitivity of the hypernuclear cross sections to two alternate, viable descriptions of the basic photoproduction process is examined in detail. The basic photoproduction operators, including nonstatic terms, are examined. These nonstatic operators come into play to excite a richer spectrum of hypernuclear states as one goes beyond zero angle and threshold production. Hypernuclear wavefunctions, based on a phenomenological λ nucleus interaction and including λ continuum effects, are used to study the role of the associated form factors in determining the production cross sections for a variety of nuclear targets, and a range of angles and energies. Hypernuclear excitations other than spin-flip modes are then found to be significantly excited and kaon distortion effects are found to strongly alter the magnitude of the cross sections. Our conclusions are compared to those found by others in earlier investigations of this reaction.