Cosmological Constant Seesaw in String/M-Theory

In this paper we extend the Cosmological Constant Seesaw treatment of hepth/0602112 to String/M-Theory where the cosmological constant is finite. We discuss how transitions between different λ, one of Planckian vacuum energy, can give rise to a large M Pl denominator in the Cosmological Constant Seesaw relation discussed by Banks, Motl and Carroll. We apply these ideas to 2d/3d String/M-Theory and show how the existence of a large N dual fermionic theory makes the demonstration of a transition between different λ relatively straight forward. We also consider 2d/3d Heterotic String/M-Theory cosmology, a theory for which the large N dual is unknown. The minisuperspace associated to these models is 26/27 dimensional for the SO(24) theory and 10/11 dimensional for the SO(8)×E8 theory and consists of the T fields as well as the dilaton and metric. 2d Heterotic String Quantum Cosmology is similar to critical string dynamics except for the inclusion of the 2d gauge fields. These 2d gauge fields have an important effect on the vacuum energy and on transitions between different λ through the effects of Wilson lines. Finally we discuss the extension to existing higher dimensional string cosmologies possessing large N duals.