A correct understanding and description of the I = 2 ππ S-wave interaction is important for the extraction of the I = 0 ππ S-wave interaction from experimental data and for understanding the I = 0 ππ S-wave interaction theoretically. With t-channel ρ, f 2 (1270) exchange and the ππ → ρρ → ππ box diagram contribution, we reproduce the ππ isotensor S-wave and D-wave scattering phase shifts and in...