One-loop adjoint masses for non-supersymmetric intersecting branes

TL;DR

The paper analyzes how softly broken supersymmetry arises in intersecting D-brane setups by a small angular deviation $2\epsilon$ from a SUSY configuration and computes the resulting one-loop masses for adjoint scalars on the brane world-volumes. It develops a dual framework: (i) a low-energy Coleman-Weinberg analysis classifies masses by $N\approx 4$ and $N\approx 2$ sectors (with $N\approx 1$ yielding no adjoint mass) and (ii) a full string-theoretic one-loop amplitude calculation that reproduces the CW results and identifies ultraviolet NS-NS tadpole artifacts that map to tree-level supergravity. The leading-order results show a universal tachyonic direction in the adjoint mass matrix for the toroidal setups, while subleading effects and moduli stabilization are expected to modify the tadpole contributions. The work clarifies how stringy effects and their supergravity counterparts align in SUSY-breaking mediation and provides a framework for evaluating the impact of tadpoles on model-building in intersecting-brane constructions.

Abstract

We consider breaking of supersymmetry in intersecting D-brane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane world-volumes. In the open string channel, the string two-point function receives contributions only from the infrared and the ultraviolet limits. The latter is due to tree-level closed string uncanceled NS-NS tadpoles, which we explicitly reproduce from the effective Born-Infeld action. On the other hand, the infrared region reproduces the one-loop mediation of supersymmetry breaking in the effective gauge theory, via messengers and their Kaluza-Klein excitations. In the toroidal set-up considered here, it receives contributions only from broken N=4 and N=2 supersymmetric configurations, and thus always leads at leading order to a tachyonic direction, in agreement with effective field theory expectations.