Absorptive effects in K+ Lambda photoproduction on nucleons and nuclei.

Abstract

Incorporating final-state correlation effects, we have reinvestigated the ${\ensuremath{\gamma}}^{1}\mathrm{H}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\Lambda}$ elementary process. Our model not only resolves the persisting trouble of the small $\mathrm{KN}\ensuremath{\Lambda}$ coupling constant, but also yields agreement with cross-section data at higher energies. Using our amplitudes, we calculate angular distributions for the reaction $^{16}\mathrm{O}(\ensuremath{\gamma}, {K}^{+})_{\ensuremath{\Lambda}}^{16}\mathrm{N}$. While the forward cross section increases with increasing energy, the total cross section is almost constant from ${E}_{\ensuremath{\gamma}}=1.2$ through 2 GeV, suggesting that rather low photon energies hold promise for exploration of hypernuclear excitations.