Soft Supersymmetry-breaking terms and the μproblem

TL;DR

This work examines how soft SUSY-breaking terms arise from Supergravity and how string theory constrains these terms, addressing the μ problem and its proposed resolutions. It introduces the goldstino angle to parametrize the SUSY-breaking source (dilaton vs moduli) and derives explicit expressions for gaugino masses, scalar masses, A-terms, and B-terms in both general and limiting cases, including dilaton-dominated and large-T Calabi–Yau/orbifold scenarios. The study shows that string-derived soft terms exhibit distinctive patterns—universal scalars in the dilaton limit, and potentially lighter gauginos or non-universal scalars in modulus-dominated cases—leading to characteristic low-energy spectra that could be tested at colliders. By detailing one-loop corrections and moduli-space effects, the paper provides a framework to interpret future SUSY spectra in terms of fundamental high-energy dynamics and SUSY-breaking origins within Supergravity and Superstring theories.

Abstract

The connection between Supergravity and the low-energy world is analyzed. In particular, the soft Supersymmetry-breaking terms arising in Supergravity, the $μ$ problem and various solutions proposed to solve it are reviewed. The soft terms arising in Supergravity theories coming from Superstring theory are also computed and the solutions proposed to solve the $μ$ problem, which are naturally present in Superstrings, are also discussed. The $B$ soft terms associated are given for the different solutions. Finally, the low-energy Supersymmetric-spectra, which are very characteristic, are obtained.