T-Quarks at the Large Hadron Collider: 2010-12

Abstract

We study the potential of the current Large Hadron Collider (LHC) 7 TeV run to search for heavy, colored vector-like fermions, which are assumed to carry a conserved Z2 quantum number forcing them to be pair-produced. Each fermion is assumed to decay directly into a Standard Model quark and an invisible stable particle. T-odd quarks (T-quarks) and the lightest T-odd particle (LTP) of the Littlest Higgs model with T-parity provide an example of this setup. We estimate the bounds based on the published CMS search for events with jets and missing transverse energy in the 35 pb-1 data set collected in the 2010 run. We find that T-quark masses below about 450 GeV are ruled out for the LTP mass about 100 GeV. This bound is somewhat stronger than the published Tevatron constraint. We also estimate the reach with higher integrated luminosities expected in the 2011-12 run. If no deviation from the SM is observed, we expect that a bound on the T-quark mass of about 650 GeV, for the LTP mass of 300 GeV and below, can be achieved with 1 fb-1 of data. We comment on the possibility of using initial-state radiation jets to constrain the region with nearly-degenerate T-quark and LTP.