Higgs Cascade Decays to $\gamma\gamma + \jet \jet$ at the LHC

Abstract

Extra light electroweak singlets can dramatically alter Higgs decays by introducing additional decay modes, $h\to aa$. In scenarios where cascade decays $h\to aa\to 4X, X\ne b,\bar b$ dominate, the Higgs will escape conventional searches and may be as light as $82 \gev$. In this paper we investigate the discovery potential of the mode $h\to aa\to 2\gamma 2g$ through direct ($pp\to h$) and associated ($pp \to W^{\pm}h$) Higgs production at the LHC. Our search covers all kinematically allowed singlet masses for $\sim 80 \gev \le m_h < 160 \gev$ and assumes an integrated luminosity $\CL = 300 {\rm fb}^{-1}$. We find associated production, despite a smaller production cross section, to be the better mode. A branching ratio $BR(h\to 2\gamma 2g) \cong 0.04$ is sufficient for discovery in the bulk of our search window. Given the same luminosity and branching ratio 0.04, direct detection fails to discover a Higgs anywhere in our search window. Discovery in the limited region $m_h > 120 \gev, m_a \sim 25 \gev$ is possible with direct production when the branching ratio is $\simge 0.06$.