## Search Capability for $\eta \to \nu_{e,{\tau}}\bar\nu_{e,{\tau}}$ Decays in Cubic Kilometer Neutrino Detectors

##### Authors
Fazely, A. R.
Gunasingha, R. M.
Imlay, R. L.
We investigate the discovery potential of cubic kilometer neutrino observatories such as IceCube to set stringent limits on the forbidden decays $\eta\to\nu_e\bar\nu_e$ and $\eta\to\nu_{\tau}\bar\nu_{\tau}$. The signatures for these decays are cascade events resulting from the charged-current reactions of $\nu_e, \nu_{\tau}$, $\bar\nu_e$ and $\bar\nu_{\tau}$ on nuclei in such detectors. Background cascade events are mainly due to $\nu_e$'s from atmospheric $\mu$, $K^+$, and $K^{0}_S$ decays and to a lesser extent from atmospheric $\nu_{\mu}$ neutral current interactions with nuclei. A direct upper limit for the branching ratio $\eta \to \nu_{e,\tau} \bar\nu_{e,\tau}$ of $4.5\times10^{-4}$ at 90% CL can be achieved.