Mini--Review of Dark Matter: 2012

TL;DR

This mini-review summarizes the evidence, candidates, and detection efforts for dark matter as of 2012, emphasizing WIMPs and the challenges in confirming their signals.

Contribution

It provides a comprehensive overview of dark matter candidates, detection methods, and discusses the concept of a WIMP safe minimal mass, highlighting current experimental challenges.

Findings

WIMPs are the primary focus of dark matter detection efforts.

Claims of positive WIMP detection are considered premature.

The concept of a WIMP safe minimal mass is introduced.

Abstract

This is the mini-review on Dark Matter in the 2012 edition of the Particle Data Group's Review of Particle Properties. After briefly summarizing the arguments in favor of the existence of Dark Matter, we list possible candidates, ranging in mass from a fraction of an eV (e.g., axions) to many solar masses (e.g., primordial black holes), and discuss ways to detect them. The main emphasis is on Weakly Interacting Massive Particles (WIMPs). A large international effort is being made to detect them directly, or else to detect their annihilation products. We explain why we consider all claims to have established a positive signal for WIMPs in either direct or indirect detection to be premature. We also introduce the concept of a {\it WIMP safe} minimal mass; below this mass, the interpretation of a given direct search experiment depends strongly on the tail of the WIMP velocity distribution and/or on the experimental energy resolution.