Electric discharge in vacuum by minicharged particles
  We discuss the possibility of a laboratory search for light minicharged particles carrying electric charge that is a small fraction $\epsilon$ of that of electron. We point out that the production of pairs of such particles in an electric field would result in a measurable discharge in vacuum of electrically charged objects. A realistic experiment may be sensitive to such particles at least down to $\epsilon \sim 10^{-8}$ if their mass is below $\sim 10^{-4}$eV. 
Xin Li and M.B. Voloshin
hep-ph hep-ex