High Energy Phenomenology Seminar: "Charged Dark Matter and Dark Catalysis"

Speaker Jakob Scholtz (Harvard)
Date: 11/17/2017
Time: 12 p.m. - 1 p.m.

222 Loomis

Event Contact: Sarah Holmes

High Energy Phenomenology Group

Event Type: Seminar/Symposium

High Energy Phenomenology Seminar:

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. These effects must be taken into account to assess the viability of darkly-charged dark matter. 

Since we have was shown that dark matter with mass of order the weak scale can be charged under a new long-range force, decoupled from the Standard Model, with only weak constraints from early Universe cosmology, we consider the implications of an additional charged particle C that is light enough to lead to significant dissipative dynamics on galactic times scales. We highlight several novel features of this model, which can be relevant even when the C particle constitutes only a small fraction of the number density (and energy density). We assume a small asymmetric abundance of the C particle whose charge is compensated by a heavy X particle so that the relic abundance of dark matter consists mostly of symmetric X\bar{X}, with a small asymmetric component made up of X and C. As the universe cools, it undergoes asymmetric recombination binding the free Cs into (XC) dark atoms efficiently. Even with a tiny asymmetric component, the presence of C particles catalyzes tight coupling between the heavy dark matter X and the dark photon plasma that can lead to a significant suppression of the matter power spectrum on small scales and lead to some of the strongest bounds on such dark matter theories. We find a viable parameter space where structure formation constraints are satisfied and significant dissipative dynamics can occur in galactic haloes but show a large region is excluded. Our model shows that subdominant components in the dark sector can dramatically affect structure formation.

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