Strictly Anomaly Mediated Supersymmetry Breaking

TL;DR

This paper explores an anomaly-mediated supersymmetry breaking model with additional U(1) symmetry, addressing the tachyonic slepton problem, neutrino masses, and Higgs sector, while analyzing its phenomenological and cosmological implications.

Contribution

It introduces a novel MSSM extension with anomaly mediation and a U(1) symmetry, providing a comprehensive analysis of its particle spectrum, inflationary behavior, dark matter, and cosmic string predictions.

Findings

Higgs mass of 125 GeV with gravitino mass 140 TeV and tan(beta)=16

Model produces a period of hybrid inflation with specific spectral index

Cosmic strings are naturally light and detectable via gravitational waves

Abstract

We consider an MSSM extension with anomaly mediation as the source of supersymmetry-breaking, and a U(1) symmetry which solves the tachyonic slepton problem, and introduces both the see-saw mechanism for neutrino masses, and the Higgs mu-term. We compare its spectra with those from so-called minimal anomaly mediated supersymmetry breaking. We find a Standard Model-like Higgs of mass 125 GeV with a gravitino mass of 140 TeV and tan(beta)=16. However, the muon anomalous magnetic moment is 3 sigma away from the experimental value. The model naturally produces a period of hybrid inflation, which can exit to a false vacuum characterised by large Higgs vevs, reaching the true ground state after a period of thermal inflation. The scalar spectral index is reduced to approximately 0.975, and the correct abundance of neutralino dark matter can be produced by decays of thermally-produced gravitinos, provided the gravitino mass (and hence the Higgs mass) is high. Naturally light cosmic strings are produced, satisfying bounds from the Cosmic Microwave Background. The complementary pulsar timing and cosmic ray bounds require that strings decay primarily via loops into gravitational waves. Unless the loops are extremely small, the next generation pulsar timing array will rule out or detect the string-derived gravitational radiation background in this model.