Frame 6: The quarks move apart, further spreading their force field.
Frame 7: The energy in the force field increases with the separation between the quarks. When there is sufficient energy in the force field, the energy is converted into a quark and an anti-quark (remember ).
Frames 8-10: The quarks separate into distinct, color-neutral particles: the D+ (a charm and anti-down quark) and D- (an anti-charm and down quark) mesons.