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Sparticle Masses from the Superconformal Anomaly

Alex Pomarol, Riccardo Rattazzi

TL;DR

This work analyzes anomaly mediated supersymmetry breaking (AMSB), where soft terms arise from the superconformal anomaly and are UV-insensitive, but the minimal scenario predicts tachyonic sleptons. To salvage AMSB, the authors develop non-decoupling mechanisms by introducing light moduli or vectorlike messenger thresholds that alter the AMSB trajectory, creating realistic, flavor-diagonal spectra they term anti-GMSB. They present explicit constructions with messenger fields and a light field X, deriving conditions for positive scalar masses and characteristic mass hierarchies, including a heavy gravitino of order $m_{3/2} \sim 10$ TeV and nonunified gaugino masses. They further explore D-term contributions from extra U(1)'s and gauge an $R$-symmetry to generate additional UV-insensitive soft terms, and propose a mu-term mechanism that avoids large $B\mu$ terms. The resulting framework makes distinctive, testable predictions for sparticle spectra and collider phenomenology, expanding the landscape beyond conventional gauge mediation while solving the flavor problem.

Abstract

We discuss a recently proposed scenario where the sparticle masses are purely mediated by gravity through the superconformal anomaly. This scenario elegantly evades the supersymmetric flavor problem since soft masses, like the anomaly, are not directly sensitive to ultraviolet physics. However, its minimal incarnation fails by predicting tachyonic sleptons. We study the conditions for decoupling of heavy threshold effects and how these conditions are evaded. We use these results to build a realistic class of models where the non-decoupling effects of ultra-heavy vectorlike matter fields eliminate the tachyons. These models have a flavor invariant superspectrum similar to that of gauge mediated models. They, however, differ in several aspects: the gaugino masses are not unified, the colored sparticles are not much heavier than the others, the mu-problem is less severe and the gravitino mass is well above the weak scale, m_{3/2} \sim 10 TeV. We also show that in models where an R-symmetry can be gauged, the associated D-term gives rise to soft terms that are similarly insensitive to the ultraviolet.

Sparticle Masses from the Superconformal Anomaly

TL;DR

This work analyzes anomaly mediated supersymmetry breaking (AMSB), where soft terms arise from the superconformal anomaly and are UV-insensitive, but the minimal scenario predicts tachyonic sleptons. To salvage AMSB, the authors develop non-decoupling mechanisms by introducing light moduli or vectorlike messenger thresholds that alter the AMSB trajectory, creating realistic, flavor-diagonal spectra they term anti-GMSB. They present explicit constructions with messenger fields and a light field X, deriving conditions for positive scalar masses and characteristic mass hierarchies, including a heavy gravitino of order TeV and nonunified gaugino masses. They further explore D-term contributions from extra U(1)'s and gauge an -symmetry to generate additional UV-insensitive soft terms, and propose a mu-term mechanism that avoids large terms. The resulting framework makes distinctive, testable predictions for sparticle spectra and collider phenomenology, expanding the landscape beyond conventional gauge mediation while solving the flavor problem.

Abstract

We discuss a recently proposed scenario where the sparticle masses are purely mediated by gravity through the superconformal anomaly. This scenario elegantly evades the supersymmetric flavor problem since soft masses, like the anomaly, are not directly sensitive to ultraviolet physics. However, its minimal incarnation fails by predicting tachyonic sleptons. We study the conditions for decoupling of heavy threshold effects and how these conditions are evaded. We use these results to build a realistic class of models where the non-decoupling effects of ultra-heavy vectorlike matter fields eliminate the tachyons. These models have a flavor invariant superspectrum similar to that of gauge mediated models. They, however, differ in several aspects: the gaugino masses are not unified, the colored sparticles are not much heavier than the others, the mu-problem is less severe and the gravitino mass is well above the weak scale, m_{3/2} \sim 10 TeV. We also show that in models where an R-symmetry can be gauged, the associated D-term gives rise to soft terms that are similarly insensitive to the ultraviolet.

Paper Structure

This paper contains 9 sections, 52 equations, 1 figure.

Table of Contents

  1. Introduction
  2. Anomaly mediated supersymmetry breaking
  3. Decoupling and non-decoupling of high-energy thresholds and the problem of tachyonic states
  4. Anti-gauge mediated supersymmetry breaking
  5. Superparticle spectrum
  6. $D$-term contributions to scalar masses
  7. The $\mu$-problem
  8. Gauging an $R$-symmetry
  9. Conclusions

Figures (1)

  • Figure 1: Soft squared-masses of the left-handed squark (solid line), the right-handed down-squark (dashed-dotted line), the left-handed slepton (dashed line) and the right-handed slepton (dotted line) normalized to the SU(2)$_L$-gaugino squared-mass as a function of Log$_{10} X$ for $N=2,3,4$ messenger multiplets.