A Small Cosmological Constant and Backreaction of Non-Finetuned   Parameters
  We include the backreaction on the warped geometry induced by non-finetuned parameters in a two domain-wall set-up to obtain an exponentially small Cosmological Constant $\Lambda_4$. The mechanism to suppress the Cosmological Constant involves one classical fine-tuning as compared to an infinity of finetunings at the quantum level in standard D=4 field theory. 
Axel Krause (Humboldt U., Berlin)