Hyper Stealth Dark Matter and Long-Lived Particles

TL;DR

This paper proposes a novel dark matter candidate from a confining SU(N) gauge theory, which can be as light as a few GeV, with unique long-lived mesons and suppressed interactions, offering new experimental detection prospects.

Contribution

It introduces a new dark matter model based on a confining gauge theory with a light baryon and long-lived mesons, connecting collider and cosmological constraints.

Findings

Dark matter candidate can be as light as a few GeV.

Dark mesons have lifetimes ranging from millimeters to kilometers.

Model predicts detectable long-lived particles at the LHC.

Abstract

A new dark matter candidate is proposed that arises as the lightest baryon from a confining $SU(N)$ gauge theory which equilibrates with the Standard Model only through electroweak interactions. Surprisingly, this candidate can be as light as a few GeV. The lower bound arises from the intersection of two competing requirements: i) the equilibration sector of the model must be sufficiently heavy, at least several TeV, to avoid bounds from colliders, and ii) the lightest dark meson (that may be the dark $\eta'$, $\sigma$, or the lightest glueball) has suppressed interactions with the SM, and must decay before BBN. The low energy dark sector consists of one flavor that is electrically neutral and an almost electroweak singlet. The dark matter candidate is the lightest baryon consisting of $N$ of these light flavors leading to a highly suppressed elastic scattering rate with the SM. The equilibration sector consists of vector-like dark quarks that transform under the electroweak group, ensuring that the dark sector can reach thermal equilibrium with the SM in the early Universe. The lightest dark meson lifetimes vary between $10^{-3} \lesssim c \tau \lesssim 10^7$~meters, providing an outstanding target for LHC production and experimental detection. We delineate the interplay between the lifetime of the light mesons, the suppressed direct detection cross section of the lightest baryon, and the scale of equilibration sector that can be probed at the LHC.