On the quantum stress tensor for extreme 2D Reissner-Nordstrom black   holes
  Contrary to previous claims, it is shown that the expectation values of the quantum stress tensor for a massless scalar field propagating on a two-dimensional extreme Reissner-Nordstrom black hole are indeed regular on the horizon. 
Roberto Balbinot, Serena Fagnocchi, Alessandro Fabbri, Sara Farese and   Jose Navarro-Salas