A Dark Sink Enhances the Direct Detection of Freeze-in Dark Matter

Abstract

We describe a simple dark sector structure which, if present, has implications for the direct detection of dark matter (DM): the Dark Sink. A Dark Sink transports energy density from the DM into light dark-sector states that do not appreciably contribute to the DM density. As an example, we consider a light, neutral fermion $\psi$ which interacts solely with DM $\chi$ via the exchange of a heavy scalar $\Phi$. We illustrate the impact of a Dark Sink by adding one to a DM freeze-in model in which $\chi$ couples to a light dark photon ${\gamma }^{\prime }$ which kinetically mixes with the Standard Model (SM) photon. This freeze-in model (absent the sink) is itself a benchmark for ongoing experiments. In some cases, the literature for this benchmark has contained errors; we correct the predictions and provide them as a public code. We then analyze how the Dark Sink modifies this benchmark, solving coupled Boltzmann equations for the dark-sector energy density and DM yield. We check the contribution of the Dark Sink $\psi$'s to dark radiation; consistency with existing data limits the maximum attainable cross section. For DM with a mass between $\text{MeV}-\mathcal{O}(10\text{ GeV})$, adding the Dark Sink can increase predictions for the direct detection cross section all the way up to the current limits.

v2: published in PRD with minor revisions. 5+3 pages, 3+1 figures, public freeze-in code at https://github.com/prudhvibhattiprolu/FreezeIn

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Cited by in corpus (14)

• Probing Benchmark Models of Hidden-Sector Dark Matter with DAMIC-M
• Minimal Dark Matter Freeze-in with Low Reheating Temperatures and Implications for Direct Detection
• DarkSide-20k sensitivity to light dark matter particles
• Search for Light Dark Matter with 259-day data in PandaX-4T
• Plasmon-enhanced Direct Detection Method for Boosted sub-MeV Dark Matter
• Sub-MeV Dark Sink Dark Matter
• Multi-messenger FIMP
• Neutrino masses and mixing from milli-charged dark matter
• Freezing-in Cannibal Dark Sectors
• Dark Matter-Electron Scattering Search Using Cryogenic Light Detectors
• Constraining the Coexistence of Freeze-in Dark Matter and Primordial Black Holes
• Genesis of baryon and dark matter asymmetries through ultraviolet scattering freeze-in
• Scattering meets absorption in dark matter detection
• Solar Reflected Dark Matter under the Influence of a Dark Magnetic Field