Sequestered Conformal Anomaly Mediation (SCAM)

TL;DR

This work analyzes Sequestered Conformal Anomaly Mediation (SCAM) in a full 5d supergravity framework to understand how anomaly-mediated SUSY breaking transfers to the 4d effective theory. It shows that no-scale structure in the 5d Kähler potential must be broken (via bulk superpotentials, boundary terms, or loop corrections) to generate a stabilizing potential and a nonzero compensator $F_{C_+}$, which in turn yield anomaly-mediated masses that are generally warped and model-dependent. The study reveals that boundary superpotentials act as sources for bulk fields and can induce non-universal, brane-localized anomaly mediation unless a bulk source fixes universal effects; it also cautions against naively integrating the 5d superpotential over the extra dimension to obtain a 4d $W_{ m eff}$. Across condensate, beta, and no-scale breaking scenarios, the authors construct 4d EFTs that reproduce the 5d results only when proper matching and warp-factor dependence are included, highlighting significant deviations from conventional 4d EFT expectations. These findings have implications for phenomenology in warped extra dimensions and for singular higher-dimensional constructions like KKLT, where the interplay of stabilization, warping, and anomaly mediation can yield rich, non-universal spectra.

Abstract

Supersymmetric models in singular extra dimensional spaces feature prominently in many interesting phenomenological models, including those derived from string theory. In this paper we explicitly derive the low energy theory of phenomenologically viable supersymmetric theories in five dimensions, and highlight several aspects of these models that are not obvious from working solely in the 4d effective theory. Important deviations arise for anomaly mediation, which is purported to be a predictive mechanism to mediate supersymmetry (SUSY) breaking that is naturally most relevant in extra dimensional theories. Despite this, most analyses of anomaly mediation have been performed in the 4d effective theory. We fill this gap in the literature by constructing stabilized supersymmetric theories in 5d and studying supersymmetry breaking and anomaly mediation. Studying Sequestered Conformal Anomaly-Mediated (SCAM) in full generality reveals important deviations from the 4d EFT expectations, particularly for the role of boundary superpotentials, the radion and the predicted universality of anomaly mediation. We discuss the requirements for viable extra dimensional models of SUSY-breaking, and demonstrate when and how the anomaly-mediated masses in 5d reduce to the naıve 4d supersymmetric result. In many cases supersymmetry is necessarily broken at the 5d level, leading to anomaly-mediated and other supersymmetry breaking masses that are not derivable in a simple supersymmetric 4d EFT, but need to be included as matching corrections. We comment on the potential implications of our methods for phenomenology and singular higher-dimensional constructions, such as the KKLT scenario.