Hunting for the top partner in the littlest Higgs model with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>T</mml:mi></mml:math>parity at the CERN LHC

Abstract

We study the littlest Higgs model with $T$ parity at the CERN LHC through pair productions of the $T$-odd top quark partner (${T}_{\ensuremath{-}}$) which decays into the top quark and the lightest $T$-odd particle. We identify the region of parameters favored by the electroweak and cosmological considerations. The signal and background events are simulated with fast detector simulation to study the discovery potential at the LHC. We find that the hemisphere analysis recently proposed by the CMS Collaboration is very useful to separate the signal from the $t\overline{t}$ background. We discuss the observability of the top tagged signal in the effective mass (${M}_{\mathrm{eff}}$) versus the transverse missing energy (${E}_{\mathrm{Tmiss}}$) plane. We show that, for all our sample parameter sets with ${M}_{{T}_{\ensuremath{-}}}\ensuremath{\le}900\text{ }\text{ }\mathrm{GeV}$, the excess of the signal over the background can be visible as a bump structure in the ${E}_{\mathrm{Tmiss}}$ distribution for $50\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at relatively high ${M}_{\mathrm{eff}}$ intervals.