S-Duality and Cosmological Constant in String Theory
arXiv:hep-th/9507063 · doi:10.1016/0370-2693(96)00227-4
Abstract
The S-duality invariance of the equations of motion of four dimensional string effective action with cosmological constant, $Î$, is studied. It is demonstrated that the S-duality symmetry of the field equations are broken for nonzero $Î$. The ``naturalness'' hypothesis is invoked to argue that $Î$ should remain small since exact S-duality symmetry will force the cosmological constant to vanish in the string effective action.
13 pages, RevTex , slightly extended version with more discussions added ( To appear in Phys. Lett. B )