Search capability for {eta}{yields}{nu}{sub e,{tau}{nu}e,{tau}}decays in cubic-kilometer neutrino detectors

We investigate the discovery potential of cubic-kilometer neutrino observatories such as IceCube to set stringent limits on the forbidden decays {eta}{yields}{nu}{sub e{nu}e} and {eta}{yields}{nu}{sub {tau}{nu}{tau}.} The signatures for these decays are cascade events resulting from the charged-current reactions of {nu}{sub e}, {nu}{sub {tau},} {nu}{sub e}, and {nu}{sub {tau}}on nuclei in such detectors. Background cascade events are mainly due to {nu}{sub e}'s from atmospheric {mu}, K{sup +}, and K{sub S}{sup 0} decays and to a lesser extent from atmospheric {nu}{sub {mu}}neutral-current interactions with nuclei. A direct upper limit for the branching ratio {eta}{yields}{nu}{sub e,{tau}{nu}e,{tau}}of 6.1x10{sup -4} at 90% CL can be achieved.