The heavy quark search at the LHC

TL;DR

This paper investigates the potential to discover heavy fourth-generation quarks ($t'$ and $b'$) at the LHC using jet mass techniques to identify hadronic decays, reducing backgrounds and enabling searches even without $b$-tagging.

Contribution

It introduces a novel jet mass technique for identifying hadronic $W$ and $t$ decays, improving background suppression in heavy quark searches at the LHC.

Findings

Backgrounds can be reduced to manageable levels using jet mass techniques.

The method allows for searches without $b$-tagging, beneficial for early LHC runs.

Analysis is relevant for heavy quarks around 600 GeV mass.

Abstract

We explore further the discovery potential for heavy quarks at the LHC, with emphasis on the $t'$ and $b'$ of a sequential fourth family associated with electroweak symmetry breaking. We consider QCD multijets, $t\bar{t}+\rm{jets}$, $W+\rm{jets}$ and single $t$ backgrounds using event generation based on improved matrix elements and low sensitivity to the modeling of initial state radiation. We exploit a jet mass technique for the identification of hadronically decaying $W$'s and $t$'s, to be used in the reconstruction of the $t'$ or $b'$ mass. This along with other aspects of event selection can reduce backgrounds to very manageable levels. It even allows a search for both $t'$ and $b'$ in the absence of $b$-tagging, of interest for the early running of the LHC. A heavy quark mass of order 600 GeV is motivated by the connection to electroweak symmetry breaking, but our analysis is relevant for any new heavy quarks with weak decay modes.