Seesaw Extended MSSM and Anomaly Mediation without Tachyonic Sleptons

TL;DR

This paper explores an extended NMSSM model that addresses tachyonic slepton issues in anomaly-mediated SUSY breaking, naturally achieves electroweak symmetry breaking, and offers distinctive phenomenological predictions for collider and dark matter studies.

Contribution

It introduces a seesaw extended MSSM model that solves tachyonic slepton problems and achieves electroweak symmetry breaking through a natural mechanism in a left-right extension.

Findings

The LSP is a Higgsino-wino mixture.

New chargino decay phenomenology.

Potential for degenerate sleptons and squarks.

Abstract

Superconformal anomalies provide an elegant and economical way to understand the soft breaking parameters in SUSY models; however, implementing them leads to the several undesirable features including: tachyonic sleptons and electroweak symmetry breaking problems in both the MSSM and the NMSSM. Since these two theories also have the additonal problem of massless neutrinos, we have reconsidered the AMSB problems in a class of models that extends the NMSSM to explain small neutrino masses via the seesaw mechanism. In a recent paper, we showed that for a class of minimal left-right extensions, a built-in mechanism exists which naturally solves the tachyonic slepton problem and provides new alternatives to the MSSM that also have automatic R-parity conservation. In this paper, we discuss how electroweak symmetry breaking arises in this model through an NMSSM-like low energy theory with a singlet VEV, induced by the structure of the left-right extension and of the right magnitude. We then study the phenomenological issues and find: the LSP is an Higgsino-wino mix, new phenomenology for chargino decays to the LSP, degenerate same generation sleptons and a potential for a mild squark-slepton degeneracy. We also discuss possible collider signatures and the feasibility of dark matter in this model.