R-parity preserving super-WIMP decays

TL;DR

This paper explores how second-order super-weak decays of super-WIMPs in a supersymmetric model can produce long lifetimes and observable signals for dark matter detection, aligning with PAMELA's recent observations.

Contribution

It introduces a model where super-WIMP decay rates depend on neutrino masses, leading to potential indirect detection signals consistent with experimental data.

Findings

Decay lifetimes can exceed the age of the Universe.

Enhanced energetic electron and positron production.

Compatibility with PAMELA's positron excess observations.

Abstract

We point out that when the decay of one electroweak scale super-WIMP state to another occurs at second order in a super-weak coupling constant, this can naturally lead to decay lifetimes that are much larger than the age of the Universe, and create observable consequences for the indirect detection of dark matter. We demonstrate this in a supersymmetric model with Dirac neutrinos, where the right-handed scalar neutrinos are the lightest and next-to-lightest supersymmetric partners. We show that this model produces a super-WIMP decay rate scaling as m_nu^4/(weak scale)^3, and may significantly enhance the fraction of energetic electrons and positrons over anti-protons in the decay products. Such a signature is consistent with the observations recently reported by the PAMELA experiment.