One Loop Soft Supersymmetry Breaking Terms in Superstring Effective Theories
Pierre Binetruy, Mary K. Gaillard, Brent D. Nelson
TL;DR
The paper provides a systematic evaluation of one-loop soft supersymmetry-breaking terms in a wide class of superstring effective theories, explicitly incorporating anomaly-mediated contributions and highlighting regulator- and moduli-dependent effects. It derives complete expressions for gaugino masses, A-terms, B-terms, and scalar masses from the underlying SUGRA data (Kähler potential, superpotential, gauge kinetic functions) while accounting for Green–Schwarz corrections and string threshold effects. In moduli-dominated scenarios at self-dual points, tree-level gaugino masses and A-terms can vanish, leaving anomaly-mediated contributions whose size and even sign depend on the chosen regularization (PV scheme), leading to regulator-sensitive scalar masses. The framework is then specialized to orbifold models, yielding explicit tree-level soft terms and demonstrating how moduli stabilization and PV regularization shape the one-loop spectrum, with implications for tachyonic sleptons and experimental discrimination between spectra. The authors also provide Higgs-mass–reference spectra and discuss strategies to distinguish between anomaly-dominated and dilaton/moduli-mediated scenarios.
Abstract
We perform a systematic analysis of soft supersymmetry breaking terms at the one loop level in a large class of string effective field theories. This includes the so-called anomaly mediated contributions. We illustrate our results for several classes of orbifold models. In particular, we discuss a class of models where soft supersymmetry breaking terms are determined by quasi model independent anomaly mediated contributions, with possibly non-vanishing scalar masses at the one loop level. We show that the latter contribution depends on the detailed prescription of the regularization process which is assumed to represent the Planck scale physics of the underlying fundamental theory. The usual anomaly mediation case with vanishing scalar masses at one loop is not found to be generic. However gaugino masses and A-terms always vanish at tree level if supersymmetry breaking is moduli dominated with the moduli stabilized at self-dual points, whereas the vanishing of the B-term depends on the origin of the mu-term in the underlying theory. We also discuss the supersymmetric spectrum of O-I and O-II models, as well as a model of gaugino condensation. For reference, explicit spectra corresponding to a Higgs mass of 114 GeV are given. Finally, we address general strategies for distinguishing among these models.