Target mass dependence of isotensor double charge exchange: Evidence for deltas in nuclei

Abstract

Measurements of forward-angle cross sections for double charge exchange on $^{16}\mathrm{O}$, $^{28}\mathrm{Si}$, and $^{40}\mathrm{Ca}$ at 164 MeV incident pion energy suggest an ${A}^{\ensuremath{-}\frac{4}{3}}$ dependence for the cross section. This $A$ dependence is shown to provide evidence for $\ensuremath{\Delta}$ components in the nuclear wave function.NUCLEAR REACTIONS $^{16}\mathrm{O}$(${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$), $^{28}\mathrm{Si}$(${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$), $^{40}\mathrm{Ca}$(${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$); ${E}_{\ensuremath{\pi}}=164$ MeV; measured $\ensuremath{\sigma}(5\ifmmode^\circ\else\textdegree\fi{})$, and mass excesses for $^{28}\mathrm{S}$ and $^{40}\mathrm{Ti}$, found ${A}^{\ensuremath{-}\frac{4}{3}}$ dependence for cross section.