Exotic Signals of Vectorlike Quarks

TL;DR

This paper explores unconventional decay modes of vectorlike quarks at the LHC, highlighting potential signals involving multiple leptons and jets, which could evade current detection strategies.

Contribution

It introduces the possibility that vectorlike quarks decay via higher-dimensional operators, leading to novel final states not thoroughly examined in previous searches.

Findings

Vectorlike quarks can decay into multiple SM fermions via higher-dimensional operators.

Certain decay channels produce distinctive multi-lepton and multi-jet signatures.

Some decay modes remain difficult to detect, leaving their masses unconstrained by current experiments.

Abstract

Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike quarks of charge 2/3 at the LHC would then lead to a variety of possible final states, including $t\bar t + 4\tau$, $t\bar b\nu + 3\tau$, $t\bar t + 4\mu$, $t\bar b\nu + 3\mu$ or $t\bar t + 4b$. Additional channels ($b\bar b + 4\tau$, $6b$, etc.) arise in the case of a vectorlike quark of charge $-1/3$. If the vectorlike quark decays into three light quarks, then the $(3j)(3j)$ signal is more difficult to observe, and the vectorlike quark mass is almost unconstrained by current searches.