Abstract
We study the reach of direct detection experiments for large bound states (containing $10^4$ or more dark nucleons) of Asymmetric Dark Matter. We consider ordinary nuclear recoils, excitation of collective modes (phonons), and electronic excitations, paying careful attention to the impact of the energy threshold of the experiment. Large exposure experiments with keV energy thresholds provide the best (future) limits when the Dark Matter is small enough to be treated as a point particle, but rapidly lose sensitivity for more extended dark bound states, or when the mediator is light. In those cases, low threshold, low exposure experiments (such as with a superfluid helium, polar material or superconducting target) are often more sensitive due to coherent enhancement over the dark nucleons. We also discuss indirect constraints on composite Asymmetric Dark Matter arising from self-interaction, formation history and the properties of the composite states themselves.
Highlights
The last decade has seen a dramatic broadening in the types of dark matter (DM) theories that are being proposed and searched for using various experiments [1,2]
We have considered the detection of nuggets of asymmetric dark matter, comparing and contrasting low threshold but low exposure proposed experiments with higher threshold but larger exposure experiments
(ii) Smaller, but lower threshold, experiments can dominate for less dense nuggets and for nuggets that interact with the standard model via a longer range mediator
Summary
The last decade has seen a dramatic broadening in the types of dark matter (DM) theories that are being proposed and searched for using various experiments [1,2]. A number of experiments have been recently proposed that are sensitive to very low momentum transfers, both for DM coupling to nucleons (see, e.g., [24,25,26,27,28,29,30]) as well as electrons (see, e.g., [31,32,33,34,35,36]); some of these experiments are sensitive to interactions via dark photons These experiments are natural places to look when searching for ADM nuggets because of their increased sensitivity via the coherent enhancement.
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