Hi, I'm working on an assignment in which the following reaction takes place: [tex] \nu_e e^- \rightarrow \nu_e e^- [/tex] And I'm wondering whether its possible to have an electron neutrino and an electron annihilate to form a [tex] W^- [/tex] boson, after which that boson decays into a [tex] \nu_e e^- [/tex] pair, satisfying the equation? From what I'm reading online it seems like W bosons only decay into electron and anti-electron neutrino pairs, but I figure as long as the lepton number is being conserved (which it is in the above reaction), I don't see any rule stating why it can't work. My general approach is that if there is no rule saying it can't work, I assume it does (I don't have any other way to operate to be honest). As far as I know I only have to worry about conservation of angular momentum, charge, baryon number, and lepton number for the reactions we're considering (this is all undergraduate level). Thanks for the help!