Wilsonian Effective Field Theory and String Theory

Understand

We argue that deriving an effective field theory from string theory requires a Wilsonian perspective with a physical cutoff.

• Employing proper time regularization we demonstrate the decoupling of states and contrast this with what happens in dimensional regularization.
• In particular we point out that even if the cosmological constant (CC) calculated from some classical action at some ultra-violet scale is negative, this does not necessarily imply that the CC calculated at cosmological scales is also negative, and discuss the possible criteria for achieving a positive CC starting with a CC at the string/KK scale which is negative.
• Obviously this has implications for swampland claims.