Long-lived heavy quarks : a review

TL;DR

This review discusses the theoretical models, experimental searches, and detection strategies for long-lived heavy quarks, emphasizing their unique signatures like displaced vertices and the need for dedicated analysis methods.

Contribution

It provides a comprehensive overview of long-lived heavy quarks, including reinterpretations of existing searches and suggestions for extending experimental sensitivity.

Findings

Long-lived heavy quarks can produce displaced vertices and bound states.

Existing searches may have missed long-lived heavy quarks due to prompt decay assumptions.

Recommendations are given to improve detection of long-lived heavy quarks.

Abstract

We review the theoretical and experimental situation for long-lived heavy quarks, or bound states thereof, arising in simple extensions of 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 quarks with 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 quarks might lead to signatures involving displaced vertices, new hadronic bound states, or decays happening outside of the detector acceptance. We perform reinterpretations of existing searches for short- and long-lived particles, and give suggestions on how to extend their reach to long-lived heavy quarks.