A Proposal for Altering the Unification Scale in String Theory

Abstract

An ensemble of short open strings in equilibrium with the heat bath provided by the Euclidean worldvolume of a stack of Dbranes undergoes a thermal phase transition to a long string phase. The transition temperature is just below the string scale. We point out that this phenomenon provides a simple mechanism within open and closed string theories for altering the strong-electro-weak coupling unification scale relative to the fundamental closed string mass scale in spacetimes with external electromagnetic background.

Comments: Latex, 7pgs. v5 Minor changes to main paper. Note added, following recent clarification of the first-order deconfining phase transition to a long string phase in the low energy finite temperature supersymmetric gauge theory limit (hep-th/0409301). Updated references. v6 Eq2 corrected