Long-Lived Heavy Quarks: A Review

We review the theoretical and experimental situation for long-lived heavy quarks, or bound statesthereof, arising in simple extensionsof the Standard Model. If these particles propagate large distances before their decay, they give rise to specific signatures requiring dedicated analysis methods. In particular, vector-like quarkswith negligible couplings to the three known families could have eluded the past experimental searches. While most analyses assume prompt decays at the production vertex, novel heavy quarksmight lead to signatures involving displaced vertices, new hadronic bound states, or decays happening outside of the detector acceptance. We perform reinterpretationsof existing searches for short- and long-lived particles, and give suggestions on how to extend their reach to long-lived heavy quarks.