π+---3H and π+---3He scattering lengths and the pion, nucleon, and nuclear mass differences

The pion-trinucleonic nucleus scattering lengths are computed on the basis of approximate four-particle equations with allowance for the mass splittings in the pion, nucleon, and nuclear isomultiplets. It is shown that allowance for the mass differences leads to the appearance in the expressions for the π---3He and π+--3H scattering lengths of imaginary parts of the order of 10-3 fm and to substantial changes in the real parts of these expressions. The results are found to depend strongly on the choice of the πN-potential parameters. There are indications that the low-energy multiple π(3N) scattering series converges slowly