Dark Matter in the Singlet Extension of MSSM: Explanation of Pamela and Implication on Higgs Phenomenology

TL;DR

This paper explores how singlino-like dark matter in an extended MSSM can explain Pamela's observations, impacts Higgs decay modes, and predicts multi-muon signals at the LHC.

Contribution

It analyzes the parameter space for singlino dark matter explanation of Pamela results and examines Higgs phenomenology constraints and signatures.

Findings

Singlet Higgs bosons can enhance couplings with the SM Higgs.

The SM-like Higgs may decay into singlet Higgs pairs instead of bar{b}.

LHC signals include multi-muon events from Higgs decays.

Abstract

As discussed recently by Hooper and Tait, the singlino-like dark matter in the Minimal Supersymmetric Standard Model (MSSM) extended by a singlet Higgs superfield can give a perfect explanation for both the relic density and the Pamela result through the Sommerfeld-enhanced annihilation into singlet Higgs bosons ($a$ or $h$ followed by $h->a a$) with $a$ being light enough to decay dominantly to muons or electrons. In this work we analyze the parameter space required by such a dark matter explanation and also consider the constraints from the LEP experiments. We find that although the light singlet Higgs bosons have small mixings with the Higgs doublets in the allowed parameter space, their couplings with the SM-like Higgs boson $h_{SM}$ (the lightest doublet-dominant Higgs boson) can be enhanced by the soft parameter $A_\kappa$ and, in order to meet the stringent LEP constraints, the $h_{SM}$ tends to decay into the singlet Higgs pairs $aa$ or $hh$ instead of $b\bar b$. So the $h_{SM}$ produced at the LHC will give a multi-muon signal, h_{SM} -> aa -> 4 muons or h_{SM} -> hh -> 4 a -> 8 muons.