Figure 6: Parameter region of the bound state formation at the collision.

(a) The black dots (red crosses) indicate the upper and lower critical values of js,1 to form the skyrmion bound state for α = 0.01 (α = 1.0) in the case (A1). The critical values of js,1 are examined at the impact parameters b = −50 ~ +50 in 10 increments. Figures (b–d) are the same as (a) but for the cases (A2), (B1) and (B2), respectively, and only the results for α = 1.0 are shown in (b,d).