Gauge Thresholds and Kaehler Metrics for Rigid Intersecting D-brane Models
Ralph Blumenhagen, Maximilian Schmidt-Sommerfeld
TL;DR
The paper computes one-loop gauge-threshold corrections for rigid intersecting D6-brane models on a Z2×Z'2 orbifold with twisted RR charges, and demonstrates that the non-holomorphic threshold pieces cancel against moduli-dependent Kähler metrics to yield a holomorphic one-loop gauge kinetic function f_a. By analyzing four annulus sectors, it derives explicit expressions for threshold corrections and extracts the holomorphic f_a^1-loop, including a universal term and sector-specific logs of η and θ-functions evaluated at complexified moduli T_i^c. It also determines Kähler metrics for vector-like and chiral bifundamental matter, and identifies universal corrections that necessitate a one-loop redefinition of twisted complex structure moduli W^c_{ikl}, tying together holomorphy, threshold behavior, and moduli dynamics. These results are relevant for incorporating D-instanton effects (e.g., E2-branes) and for moduli-stabilization scenarios in globally consistent string vacua. The work extends prior local results to global models with broader twisted-charge sectors, and provides concrete tools for gauge coupling unification and non-perturbative superpotential contributions in realistic D-brane setups.
Abstract
The gauge threshold corrections for globally consistent Z2 x Z2' orientifolds with rigid intersecting D6-branes are computed. The one-loop corrections to the holomorphic gauge kinetic function are extracted and the Kaehler metrics for the charged chiral multiplets are determined up to two constants.