Looking for a light Higgs boson in the overlooked channel

Abstract

The final state obtained when a Higgs boson decays to a photon and a Z boson has been mostly overlooked in current searches for a light Higgs boson. However, when the Z boson decays leptonically, all final state particles in this channel can be measured, allowing for accurate reconstructions of the Higgs mass and angular correlations. We determine the sensitivity of the Large Hadron Collider (LHC) running at center of masses energies of 8 and 14 TeV to Standard Model (SM) Higgs bosons with masses in the 120 - 130 GeV range. For the 8 TeV LHC, sensitivity to several times the the SM cross section times branching ratio may be obtained with 20 inverse femtobarns of integrated luminosity, while for the 14 TeV LHC, the SM rate is probed with about 100 inverse femtobarns of integrated luminosity.

Figures (4)

• Figure 1: Feynman diagrams contributing to $q\bar{q}\to \ell\bar{\ell}\gamma$ are shown in (a) and (b).
• Figure 2: Signal (red, solid) and background (blue, dashed) distributions in $\cos \Theta$, $\phi$ and $\cos \theta$, with $\sqrt{\hat{s}} = m_h = 125$ GeV.
• Figure 3: Exclusion limits at the 95% confidence level on the Higgs production rate times branching fraction to $Z\gamma$ at the $8$ TeV LHC with an integrated luminosity of 20 fb$^{-1}$. The green (yellow) band is the 1(2) $\sigma$ contour. The solid red line corresponds to the SM expectation.
• Figure 4: Exclusion limits at the 95% confidence level on the Higgs production rate times branching fraction to $Z\gamma$ at the $14$ TeV LHC with an integrated luminosity of $100$ fb$^{-1}$. The green (yellow) band is the 1(2) $\sigma$ contour. The solid red line corresponds to the SM expectation.