[Paper Review] US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

M. Battaglieri, Belloni, Alberto+249 more|arXiv (Cornell University)|Jul 14, 2017

Dark Matter and Cosmic PhenomenaPhysics and Astronomy176 citations

TL;DR

A community white paper outlining the rationale, scope, and proposed small-scale dark matter experiments (≃$10M) to complement the G2 program, covering hidden-sector and ultra-light dark matter with multiple experimental approaches.

ABSTRACT

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.

Motivation & Objective

• Motivate a multi-faceted small-experiments program to explore beyond-WIMP dark matter candidates.
• Highlight two broad frameworks—Hidden-Sector DM and Ultra-Light DM—as primary targets for new experiments.
• Identify high-value parameter space and experimental approaches that can be pursued with modest funding.
• Promote synergy between theory and diverse experimental techniques across direct detection, accelerators, and astrophysical probes.

Proposed method

• Survey and organize a broad landscape of small-scale dark matter proposals and results from the US and international community.
• Classify approaches by mass range, interaction type, and experimental technology to target complementary regions of parameter space.
• Present a programmatic case for low-threshold detection, axion searches, fixed-target experiments, and ultra-light field-based detection methods.
• Outline facilities, projected sensitivities, and short-to-medium term timelines for small-scale experiments.
• Discuss theoretical guidance and anomalies (muon g-2, Be-8, etc.) to motivate targeted experiments.

Experimental results

Research questions

• RQ1 What are the most motivated dark matter candidates beyond WIMPs that can be probed with small-scale experiments?
• RQ2 How can a portfolio of low-cost experiments collectively cover key regions of hidden-sector and ultra-light dark matter parameter space?
• RQ3 What experimental technologies and facilities enable probing of sub-GeV to ultra-light dark matter within a few years?
• RQ4 How can theory, nuclear/atomic/condensed matter physics insights enhance dark matter searches across direct detection, accelerators, and astrophysical probes?
• RQ5 What complementarities among direct detection, accelerator-based searches, and coherent-field methods maximize discovery potential?

Key findings

• Low-threshold direct detection and low-mass detectors can probe hidden-sector freeze-in and ultra-light DM with gram-scale targets.
• A suite of diverse technologies is required to cover the full QCD axion mass range and various hidden-sector mediator masses.
• Fixed-target and accelerator experiments offer robust probes of sub-GeV DM and related forces within modest funding and timelines.
• Existing anomalies (e.g., Be-8, muon g-2) and LIGO observations motivate targeted small experiments for new bosons and dark matter self-interactions.
• Theory advances are crucial to exploiting cosmological data and guiding novel experimental connections to nuclear, atomic, and condensed matter physics.