Model-independent analysis of soft masses in heterotic string models with anomalous U(1) symmetry

TL;DR

This work addresses how soft SUSY breaking masses behave in heterotic string models with an anomalous U(1) symmetry, without committing to a specific SUSY-breaking mechanism. By analyzing the general SUGRA structure and incorporating S, M^i, and charged matter with U(1)_A charges, the authors compare D-term and F-term contributions to scalar masses, and derive how gaugino masses and A-terms arise under broad assumptions. They find that D-term contributions to scalar masses are typically comparable to or larger than F-term contributions (barring the universal piece), and they present three SUSY-breaking regimes with characteristic hierarchies among $(m^2)_k$, $M_a$, and $A_{kll'}$. The results illuminate how anomalous U(1) D-terms can destroy sfermion mass universality and influence FCNC, while outlining possible model-building avenues to achieve viable phenomenology in string-derived frameworks.

Abstract

We study the magnitudes of soft masses in heterotic string models with anomalous U(1) symmetry model-independently. In most cases, D-term contribution to soft scalar masses is expected to be comparable to or dominant over other contributions provided that supersymmetry breaking is mediated by the gravitational interaction and/or an anomalous U(1) symmetry and the magnitude of vacuum energy is not more than of order $m_{3/2}^2 M^2$.