Rare η decays induced by new particles

The effects of new particles on η decays are considered. It is found that measurements or bounds at the level of 10-7-10-10 for the branching ratios of η → nothing, η → e+e- and η → π l υ yield interesting limits on leptoquark couplings if these particles are heavier than ∼ 300 GeV. Bounds at levels below 10-4 for η → γ e+e-, η → γ + nothing limit couplings of new neutral gauge bosons. We compare the information from η decays and that of other processes (data)