Dynamical gauge coupling unification from moduli stabilization

TL;DR

This paper demonstrates that in D-brane models with KKLT stabilization, gauge couplings unify dynamically at high energy scales due to universal cycle-volume moduli, and moduli-mediated gaugino masses are naturally universal and comparable to anomaly-mediated masses.

Contribution

It shows that gauge coupling unification and mirage mediation of soft masses can occur naturally in D-brane models with KKLT stabilization, regardless of the detailed Kähler potential.

Findings

Cycle-volume moduli have universal VEVs up to small suppressed deviations.

Gauge couplings unify at high energy scale due to moduli stabilization.

Gaugino masses are universal and comparable to anomaly-mediated masses.

Abstract

In D-brane models, different part of the 4-dimensional gauge group might originate from D-branes wrapping different cycles in the internal space, and then the standard model gauge couplings at the compactification scale are determined by different cycle-volume moduli. We point out that those cycle-volume moduli can naturally have universal vacuum expectation values up to small deviations suppressed by 1/8\pi^2 if they are stabilized by KKLT-type non-perturbative superpotential. This dynamical unification of gauge couplings is independent of the detailed form of the moduli K\"ahler potential, but relies crucially on the existence of low energy supersymmetry. If supersymmetry is broken by an uplifting brane as in KKLT compactification, again independently of the detailed form of the moduli K\"ahler potential, the moduli-mediated gaugino masses at the compactification scale are universal also, and are comparable to the anomaly-mediated gaugino masses. As a result, both the gauge coupling unification at high energy scale and the mirage mediation pattern of soft supersymmetry breaking masses are achieved naturally even when the different sets of the standard model gauge bosons originate from D-branes wrapping different cycles in the internal space.