Which hadronic decay modes are good for $\eta_b$ searching: double   $J/\psi$ or something else?
  It has been controversial whether $\eta_b$ can be discovered in Tevatron Run 2 through the decay $\eta_b\to J/\psi J/\psi$ followed by $J/\psi\to \mu^+\mu^-$. We clear this controversy by an explicit calculation which predicts ${\rm Br}[\eta_b\to J/\psi J/\psi]$ to be of order $10^{-8}$. It is concluded that observing eta_b through this decay mode in Tevatron Run 2 is rather unrealistic. The eta_b may be observed in the forthcoming LHC experiments through the 4-lepton channel, if the background events can be significantly reduced by imposing some kinematical cuts. By some rough but plausible considerations, we find that the analogous decay processes eta_b to VV, D^*\bar{D}^* also have very suppressed branching ratios, nevertheless it may be worth looking for \eta_b at LHC and Super B factory through the decay modes \eta_b \to K_S K^{\pm}\pi^{\mp}, D^*\bar{D}. 
Yu Jia