Signature of a πNNresonance in pionic double charge exchange at low energies

All currently available data on the pionic double charge exchange reaction (${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) on nuclei exhibit a very peculiar energy dependence near ${\mathit{T}}_{\mathrm{\pi }}$=50 MeV, while the angular distributions behave quite regularly. We demonstrate that these features find their natural explanation by a narrow resonance in the πNN subsystem with ${\mathit{J}}^{\mathit{P}}$=$0^{\mathrm{-}}$ and a mass of 2.065 GeV.