The PAMELA and Fermi signals from long-lived Kaluza-Klein dark matter

TL;DR

This paper introduces a modified universal extra dimension model with small curvature, where long-lived Kaluza-Klein dark matter decays into leptons, potentially explaining cosmic-ray excesses observed by PAMELA and FERMI.

Contribution

It presents a new extension of the UED model with explicit KK-parity breaking, allowing KK dark matter decay into leptons, aligning with cosmic-ray observations.

Findings

KK dark matter decay explains PAMELA and FERMI excesses

Model suppresses quark decay channels

Long-lived KK dark matter fits cosmic-ray data

Abstract

We propose a simple extension of the minimal universal extra dimension (UED)model by introducing a small curvature. The model is formulated as a small anti-de Sitter curvature limit of the five-dimensional standard model (SM) in the Randall-Sundrum background geometry. While the lightest Kaluza-Klein (KK) particle can be thermal relic dark matter as usual in the UED model, the KK-parity is explicitly broken in the presence of the small curvature and the KK dark matter decays into the SM fermions with a long lifetime. Couplings of the KK dark matter with SM fermion pairs in the five dimensional bulk are controlled by fermion bulk masses. With a suitable choice of bulk masses for leptons and quarks, the KK dark matter through its decay into leptons can account for the cosmic-ray electron/positron excesses reported by the recent PAMELA and FERMI satellite experiments, while suppressing the decay into quarks.