[neutralino]

Originally Posted by dipayankar

No mass, no charge, no interactions with any force... tell me Prof, why are we studying neutrinos? They do not seem to make any difference at all to anything right?

You're correct that neutrinos have no charge, and you may be correct that they have no mass (currently it is believed that neutrinos have a very small, non-zero mass, but that may be open for debate in the coming years), but neutrinos do interact via a force: they interact via the weak force. In fact, according to hyperphysics the neutrino was first postulated to make up for the energy gap in beta decay (the decay of a neutron to a proton via the weak force). Of course, if the neutrino really does have a nonzero mass then it will interact via gravity too, but this will be extremely weak.