Resonance-like coherent production of a pion pair in the reaction in the GeV region

The reaction was studied at 0.8-2.0 GeV proton beam energies with the ANKE magnetic spectrometer at the COSY synchrotron storage ring. The proton-deuteron pairs emerging with high momenta, 0.6-1.8 GeV/c , were detected at small angles with respect to the proton beam. Distribution over the reaction missing mass reveals a local enhancement near the threshold of the pion pair production specific for the so-called ABC effect. The enhancement has a structure of a narrow bump placed above a smooth continuum. The invariant mass of the system in this enhancement region exhibits a resonance-like peak at GeV/c 2 with the width GeV/c 2 . A possible interpretation of these features is discussed.