Dark matter in natural supersymmetric extensions of the Standard Model

TL;DR

This paper investigates extensions of the MSSM with singlet fields to explain cosmic ray positron excesses and reduce fine-tuning, proposing a model that aligns dark matter annihilation signals with observed astrophysical data.

Contribution

It introduces a singlet-extended MSSM framework that simultaneously addresses the positron excess and the little hierarchy problem without requiring light scalars.

Findings

The model can fit PAMELA positron data with dark matter annihilation.

Including a singlet reduces the model's fine-tuning.

The setup predicts a light axion without light CP-even scalars.

Abstract

We explore the dark matter sector in extensions of the Minimal Supersymmetric Standard Model (MSSM) that can provide a good fit to the PAMELA cosmic ray positron excess, while at the same time addressing the little hierarchy problem of the MSSM. Adding a singlet Higgs superfield, S, can account for the observed positron excess, as recently discussed in the literature, but we point out that it requires a fine-tuned choice for the parameters of the model. We find that including an additional singlet allows both a reduction of the weak-scale fine-tuning, and an interpretation of the cosmic ray observations in terms of dark matter annihilations in the galactic halo. Our setup contains a light axion, but does not require light CP-even scalars in the spectrum.