Signature of a pi NN resonance in pionic double charge exchange at low energies.

All currently available data on the pionic double charge exchange reaction ([pi][sup +],[pi][sup [minus]]) on nuclei exhibit a very peculiar energy dependence near [ital T][sub [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 [pi][ital NN] subsystem with [ital J][sup [ital P]]=0[sup [minus]] and a mass of 2.065 GeV.