Optimal Fermi-averaging for the image t-matrix in Λ-hypernuclear production from (image) reactions Original Research Article

In order to describe Λ quasi-free production spectra from (π+,K+) reactions, we propose an optimal Fermi-averaging for the elementary π++n→K++Λ t-matrix in a nucleus under the on-energy-shell condition. We calculate these quasi-free spectra for (π+,K+) reactions on a 12C target at pπ=1.20 GeV/c and 1.05 GeV/c, and compare them with experimental data. The results show that the shape and magnitude of the spectra can explain the data, because the optimal Fermi-averaged t-matrix gives a good description of the energy-dependence in the spectra. The Λ quasi-free spectra on a heavier 28Si target are also discussed.