Amplitude-induced critical behavior of quantized vortices in the nonlinearSchrodinger equation

We studied the dynamics of quantized vortices within the context of the gen eralized nonlinear Schrodinger equation, where a vortex is represented by a coherent circular dip in a homogeneous background field with an intensity beta. We found the critical role of background field on the vortex stabilit y as follows. For beta > beta (c), a vortex is stable with a finite core si ze, exhibiting a certain critical behavior as beta --> beta (c). For beta < <beta>(c), vortices become unstable, turning into an ever-expanding circul ar kink. (C) 2000 Elsevier Science B.V. All rights reserved.