2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/73003The authors have found an error in their argument, so this paper is withdrawn.The authors have found an error in their argument, so this paper is withdrawnAnalysis of PDEsMathematical Physics35Q55$L^2$ blowup solutions of cubic NLS on $\R^2$ concentrate a fixed amount of masstext