ARE DIRECTED WAVES MULTIFRACTAL

Wave propagation is studied in a sufficiently anisotropic random mediu m where backscattering along one direction can be neglected. A Fokker- Planck equation, the solution to which would provide a complete statis tical description of such directed waves, is derived. The Fokker-Planc k equation is mapped onto an su(1,1) ferromagnet and its symmetries ar e identified. Using the symmetries, asymptotic wave function distribut ions are computed and used to show that directed wave functions fill s pace uniformly and do nor have multifractal character. [S0031-9001(98) 07511-5].