2002 年 78 巻 8 号 p. 784-787
It is shown that the interaction of large amplitude electromagnetic waves with a relativistic electron-positron plasma leads to a bunching of mass, energy, and angular momentum in stable, long-lived structures. This structure contains a quantized angular momentum, and is called Vortex soliton. The correspondence between the nonlinear Schrdinger equation and Euler equation is reviewed. Problem related with the creation of angular momentum is also addressed.