Are There any Massless Fermions?

Does a massless fermion exist? If not, why?
- Anonymous

Hi Anything,

We haven't found any yet.  Even the neutrinos have finite masses.   As far as I know there is no reason not to have massless neutrinos since there are zero rest mass solutions to the Dirac Equation which seem valid. 

There are three known neutrinos associated with the electron, muon, and tau.   What is known about neutrino masses is two differences amongst the three. That implies, in principle, that the lowest mass could be zero.  We don't know yet.

 

LeeH

 

(published on 01/25/2014)