Main Question or Discussion Point
The top quark has mass around 173GeV. The Higgs boson (probably) has only 125GeV. Why the top quark has been discovered earlier despite it has larger mass? Why did we need more powerful accelerator to detect a lighter particle? Is it possible that there are some other light particles within our accelerators' range that have not been discovered? What mass ranges have actually been searched to exclude the existence of particles in them?