Schwinger pair creation in Dirac semimetals in the presence of external   magnetic and electric fields
  We discuss the Schwinger pair creation process for the system of massless Dirac fermions in the presence of constant external magnetic and electric fields. The pair production rate remains finite unlike the vacuum decay rate. In the recently discovered Dirac semimetals, where the massless Dirac fermions emerge, this pair production may be observed experimentally through the transport properties. We estimate its contribution to the ordinary conductivity of the semimetals. 
R.A. Abramchuk, M.A.Zubkov
cond-mat.mes-hall hep-ph