Exotic Signals of Vectorlike Quarks

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 $t\bar{t}+4\ddot{I}„$, $t\bar{b}\hat{I}½+3\ddot{I}„$, $t\bar{t}+4\hat{I}¼$, $t\bar{b}\hat{I}½+3\hat{I}¼$ or $t\bar{t}+4b$. Additional channels ($b\bar{b}+4\ddot{I}„$, $6b$, 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.

6 pages, 5 figures. v2: Discussion of radiative decays and references included. Mixing values and Figure 2 corrected. v3: minor improvements on collider discussion, published version