Δ mass in quasifree Δ production from 12C

The quasifree Δ++ production mechanism in charge exchange reactions on the 12C nucleus has been studied here in the framework of the DWIA. In this study, the Δ++ is assumed to be produced in a one-step process through the elementary pp→nΔ++ reaction. Since the charge exchange reaction on a nucleus is localized in the low density region, the Lagrangian for describing the Δ excitation in the nucleus is taken from the study of the free pp→nΔ++ reaction. The present calculation explores the Δ mass in the nucleus phenomenologically, so that the calculated results could reproduce both the π+p invariant mass distribution and the ejectile energy distribution spectra