Abstract
We analyze a recently proposed extension of the Standard Model based on the $SU(4)\ifmmode\times\else\texttimes\fi{}SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{X}$ gauge group, in which baryon number is interpreted as the fourth color and dark matter emerges as a neutral partner of the ordinary quarks under $SU(4)$. We show that under well-motivated minimal flavor-violating assumptions the particle spectrum contains a heavy dark matter candidate which is dominantly the partner of the right-handed top quark. Assuming a standard cosmology, the correct thermal relic density through freeze-out is obtained for dark matter masses around 2--3 TeV. We examine the constraints and future prospects for direct and indirect searches for dark matter. We also briefly discuss the LHC phenomenology, which is rich in top quark signatures, and investigate the prospects for discovery at a 100 TeV hadron collider.
Highlights
The particle identity of the dark matter (DM) is among the most pressing questions confronting particle physics today
It is clear that DM requires an extension of the Standard Model (SM) and it is likely that an understanding of how DM fits into the context of the SM will offer hints about the underlying structure which gave rise to it
If the mass of the lightest of such states is chosen to be a few GeV and the gauge structure is supplemented by additional UV interactions, a picture in which the DM number density is determined by a primordial particle-anti-particle asymmetry connected to the asymmetry in baryon number can be realized
Summary
The particle identity of the dark matter (DM) is among the most pressing questions confronting particle physics today. If the mass of the lightest of such states is chosen to be a few GeV and the gauge structure is supplemented by additional UV interactions, a picture in which the DM number density is determined by a primordial particle-anti-particle asymmetry connected to the asymmetry in baryon number can be realized This asymmetric limit is interesting, and has a few weak points. Perhaps even more unwieldy is the need to introduce an additional sector of light states into which the DM can annihilate (or live with extreme tuning of parameters) to deplete its primordial symmetric component, a generic issue for models of asymmetric DM [13] These concerns are largely ameliorated if the DM is much heavier and its density is symmetric, resulting from its interactions with the SM quarks freezing out at much higher temperatures.
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