Results of the parameter study regarding the size of planetesimals R_pl. Left: planetesimal accretion rate shown as a colour contour on a plane of the semi-major axis of the migrating protoplanets and the radius of the planetesimals, The analytically predicted inner and outer boundaries of the sweet spot are indicated with solid and dashed lines, respectively. The red lines are for j = 2 and the green lines are for j = 3. Right: total mass of captured planetesimals as a function of the planetesimal radius.