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Minimal Dark Matter predictions and the PAMELA positron excess

Marco Cirelli, Alessandro Strumia

TL;DR

Minimal Dark Matter (MDM) adds a single electroweak multiplet to the Standard Model, yielding a stable dark matter candidate with a mass fixed by cosmology and no free particle-physics parameters. The viable candidate is a fermionic five-plet with zero hypercharge, predicting a mass of about $M\approx 9.6\,\mathrm{TeV}$ and a calculable indirect-detection signature enhanced by Sommerfeld effects for low-velocity annihilations to $W^+W^-$ and loop-induced photons. Annihilations produce observable $e^+$ and $\bar{p}$ spectra after propagation, allowing comparison with PAMELA data; a good fit at $M$ near $10$ TeV requires modest boost factors and yields falsifiable predictions for future observations and potential astrophysical constraints from the galactic center.

Abstract

We present Minimal Dark Matter and its univocal predictions for Dark Matter observables. During the idm2008 conference, PAMELA presented preliminary results showing an excess in the positron fraction: we find a good agreement, with a modest astrophysical boost factor.

Minimal Dark Matter predictions and the PAMELA positron excess

TL;DR

Minimal Dark Matter (MDM) adds a single electroweak multiplet to the Standard Model, yielding a stable dark matter candidate with a mass fixed by cosmology and no free particle-physics parameters. The viable candidate is a fermionic five-plet with zero hypercharge, predicting a mass of about and a calculable indirect-detection signature enhanced by Sommerfeld effects for low-velocity annihilations to and loop-induced photons. Annihilations produce observable and spectra after propagation, allowing comparison with PAMELA data; a good fit at near TeV requires modest boost factors and yields falsifiable predictions for future observations and potential astrophysical constraints from the galactic center.

Abstract

We present Minimal Dark Matter and its univocal predictions for Dark Matter observables. During the idm2008 conference, PAMELA presented preliminary results showing an excess in the positron fraction: we find a good agreement, with a modest astrophysical boost factor.

Paper Structure

This paper contains 3 sections, 3 equations, 1 figure.

Table of Contents

  1. Introduction
  2. Minimal Dark Matter
  3. Indirect signatures and the PAMELA positron excess

Figures (1)

  • Figure 1: html:<A name="ref-fig:PAMELA">html:</A> LAB: fig:PAMELA The PAMELA preliminary data PAMELA compared with the fermion 5-plet MDM prediction, at the best-fit point for the astrophysical parameters.