The $E_6$ inspired isosinglet quark and the Higgs boson

We consider the experimental implications of the down type isosinglet quark, $D$, predicted by the $E_{6}$, group to Higgs boson searches at the LHC. The pair production of $D$ quarks at the LHC and their subsequent decays $D\to h d$ and $D\to W u$ has been analyzed. For a light Higgs boson of mass O(120 GeV), an analysis based on fast simulation of the ATLAS detector response shows that, the $b\bar{b}$ channel becomes as efficient as the $\gamma\gamma$ channel for discovering the Higgs particle if $m_{D}<630$ GeV.