Cosmology and Astrophysics of Minimal Dark Matter

TL;DR

Minimal Dark Matter (MDM) posits DM as a single SU(2)$_L$ multiplet with zero hypercharge that interacts only through SM gauge bosons. Requiring the observed relic density fixes the DM mass scale, and non-perturbative Sommerfeld corrections raise the viable mass for multiplets such as the fermion $5$-plet from $4.4$ TeV to about $10$ TeV, while enhancing indirect-detection signals. The framework also predicts distinctive ultra-high-energy signatures, including charged tracks from ${\rm DM}^{\pm}$ crossing the Earth, potentially detectable by neutrino telescopes. Together these results connect TeV-scale particle physics to multi-messenger astrophysical probes, guiding future collider, direct-detection, and astrophysical searches.

Abstract

We consider DM that only couples to SM gauge bosons and fills one gauge multiplet, e.g. a fermion 5-plet (which is automatically stable), or a wino-like 3-plet. We revisit the computation of the cosmological relic abundance including non-perturbative corrections. The predicted mass of e.g. the 5-plet increases from 4.4 TeV to 10 TeV, and indirect detection rates are enhanced by 2 orders of magnitude. Next, we show that due to the quasi-degeneracy among neutral and charged components of the DM multiplet, a significant fraction of DM with energy E > 10^17 eV (possibly present among ultra-high energy cosmic rays) can cross the Earth exiting in the charged state and may in principle be detected in neutrino telescopes.

Figures (10)

• Figure 1: Iso-contours of the non-perturbative Sommerfeld correction to the DM DM annihilation. Here $\alpha$ is the coupling constant, $\beta$ is the DM velocity, $\epsilon$ is the ratio between the vector mass and the DM mass. The labels indicate where some classes of DM candidates lie in this plane: 'weak' indicates weak-scale DM particles, 'TeV' indicates DM with multi-TeV mass, and 'strong' indicates strongly-interacting particles that in some models give dominant co-annihilations. Within the shaded region thermal masses dominate over masses, effectively shifting the value of $\alpha/\epsilon$ as indicated by the arrow.
• Figure 2: The fermion triplet with zero hypercharge ('wino'). Fig. \ref{['fig:F30']}a (upper left): our result for its cosmological freeze-out DM abundance as function of the DM mass. Fig. \ref{['fig:F30']}c (upper right) show an example (for the indicated mass $M$) of the temperature dependence of the DM DM annihilation cross section, and fig. \ref{['fig:F30']}d (lower right) shows the resulting cosmological evolution of the DM abundance. Fig. \ref{['fig:F30']}b (lower left) shows our result for DM$^0$ DM$^0$ annihilation cross section relevant for indirect DM detection, as discussed in section \ref{['indirect']}. In each case, the continuous line is our full result, while the dashed line is the result obtained without including non-perturbative effects.
• Figure 3: The scalar triplet with zero hypercharge. Plots have the same meaning as in fig. \ref{['fig:F30']}.
• Figure 4: The fermion quintuplet with zero hypercharge. Plots have the same meaning as in fig. \ref{['fig:F30']}.
• Figure 5: Cosmological freeze-out abundance of the fermion doublet with $Y=1/2$ ('Higgsino'). Plots have the same meaning as in fig. \ref{['fig:F30']}, except that since non-perturbative corrections negligibly affect the cosmological abundance we do not show details of the computations.