The Search for Stable, Massive, Elementary Particles

TL;DR

This review surveys various experimental and observational efforts to detect stable, massive elementary particles beyond electrons and protons, highlighting knowns, unknowns, and promising directions for future research.

Contribution

It compiles and analyzes diverse search methods for stable, massive elementary particles, guiding future experimental and observational efforts.

Findings

Multiple search techniques have placed constraints on particle properties.

No definitive detection of such particles has been reported yet.

Certain parameter spaces remain promising for future searches.

Abstract

In this paper we review the experimental and observational searches for stable, massive, elementary particles other than the electron and proton. The particles may be neutral, may have unit charge or may have fractional charge. They may interact through the strong, electromagnetic, weak or gravitational forces or through some unknown force. The purpose of this review is to provide a guide for future searches - what is known, what is not known, and what appear to be the most fruitful areas for new searches. A variety of experimental and observational methods such as accelerator experiments, cosmic ray studies, searches for exotic particles in bulk matter and searches using astrophysical observations is included in this review.