Kaon photoproduction from nuclei in a relativistic nuclear model

Abstract

The formation of hypernuclei through the photoproduction of kaons is formulated in the framework of a relativistic distorted wave impulse approximation. The basic production operator is based on diagrammatic techniques and includes low-lying baryon and meson resonances. Relativistic single-particle wave functions obtained by solving the Dirac equation with scalar and timelike vector potentials are employed to describe the nucleon and hyperon bound states. The nuclear and hypernuclear structure is described in a pure single-particle single-hole model. Evaluating the matrix elements in momentum space allows straightforward treatment of Fermi motion and naturally includes nonlocalities arising from the production operator. Different nonrelativistic limits involving the upper and lower component of the Dirac wave function and a p/M expansion of the operator are investigated. The final-state interaction of the weakly absorbed kaon is incorporated via an optical potential. A variety of angular distributions for p-shell nuclei is presented and the sensitivity of the hypernuclear cross sections to the elementary operator is shown to be important. Relativistic effects are found to be important along with effects of nonlocalities for low-spin states while high-spin states with large cross sections are less affected. Kaon distortion for p-shell nuclei only provides a slight reduction in cross section for most transitions.