Influence of pp pi ions on pion absorption in H-2

The existence of three-body resonances in the molecular ion pp pi has been shown by means of a variational calculation in Jacobi coordinates. The rela tivistic and strong-force corrections to the Coulombic binding energies and the decay widths of the resonances have been calculated. We consider two m echanisms that supply the p pi atom with large kinetic energies before the moment of pion absorption by the proton, with significant impact on the int erpretation of experiments measuring the mass difference m(pi)- (-)m(pi 0) from pion absorption in pionic atoms. These mechanisms are (a) the formatio n and subsequent Coulomb decay of the metastable pp pi states and (b) pion absorption from the molecular pp pi state, giving, respectively, a discrete or a continuous distribution of kinetic energies of the resulting p pi ato ms. [S1050-2937(99)05005 1].