Search for a standard-model-like Higgs boson with a mass in the range 145 to 1000 GeV at the LHC

TL;DR

This CMS study searches for a SM-like Higgs boson in the high-mass region $m_{H}$ between $145$ and $1000$ GeV using $H\to WW$ and $H\to ZZ$ decays across multiple final states. It combines data from $7$ and $8$ TeV runs with sophisticated event selection, mass reconstruction, and background-control strategies, including data-driven sidebands and sophisticated discriminants. The analysis finds no significant signal and sets 95% CL upper limits on $\sigma_H \times \mathcal{B}$, excluding a SM-like Higgs in $145 < m_{H} < 710$ GeV and extending previous exclusions up to $710$ GeV. These results constrain high-mass Higgs scenarios and contribute to the global Higgs boson landscape by narrowing the allowed high-mass region while corroborating the discovery at $125$ GeV.

Abstract

A search for a standard-model-like Higgs boson in the H to WW and H to ZZ decay channels is reported, for Higgs boson masses in the range 145 < m[H] < 1000 GeV. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 5.3 inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the LHC. The combined upper limits at 95% confidence level on products of the cross section and branching fractions exclude a standard-model-like Higgs boson in the range 145 < m[H] < 710 GeV, thus extending the mass region excluded by CMS from 127-600 GeV up to 710 GeV.

Figures (11)

• Figure 1: (top) Distributions of $m_{\ell\ell}$ in the 0-jet different-flavor category of the $\mathrm{W}\mathrm{W} \to \ell\nu\ell\nu$ channel for data (points with error bars), for the main backgrounds (stacked histograms), and for a SM Higgs boson signal with $m_{{H}\xspace}= 500\,\text{Ge\spaceV}\xspace$. The standard preselection is applied. (bottom) BDT-classifier distributions for signal and background events for a SM Higgs boson with $m_{{H}\xspace}=500\,\text{Ge\spaceV}\xspace$ and for the main backgrounds in the 0-jet different-flavor category after requiring $80 < m_\mathrm{T}\xspace^{\ell\ell,E_{\mathrm{T}}^{\text{miss}}\xspace} < 500\,\text{Ge\spaceV}\xspace$ and $m_{\ell\ell} < 500\,\text{Ge\spaceV}\xspace$.
• Figure 2: Observed (solid line) and expected (dashed line) 95% CL upper limit on the ratio of the product of production cross section and branching ratio to the SM expectation for the Higgs boson obtained using the asymptotic CL$_{\textrm{S}}$ technique Junk:1999kvRead1 in the $\mathrm{W}\mathrm{W} \to \ell\nu\ell\nu$ channel. The 68% ($1\sigma$) and 95% ($2\sigma$) CL ranges of expectation for the background-only model are also shown with green and yellow bands, respectively. The horizontal solid line at unity indicates the SM expectation. Color figure online.
• Figure 3: Invariant mass distributions for the $m_{{H}\xspace}=500\,\text{Ge\spaceV}\xspace$ mass hypothesis, (${\mu}$, 2 jets) category in the ${H}\xspace \to \mathrm{W}\mathrm{W} \to \ell\nu {q}{q}$ channel. (top) The dijet invariant mass distribution with the major background contributions. The vertical lines correspond to the signal region of this analysis $65 < m_\mathrm{jj}\xspace < 95\,\text{Ge\spaceV}\xspace$. (bottom) The $\mathrm{W}\mathrm{W}$ invariant mass distribution with the major background contributions in the signal region.
• Figure 4: Observed (solid line) and expected (dashed line) 95% CL upper limit on the ratio of the product of production cross section and branching fraction to the SM expectation for the Higgs boson in the WW semileptonic channel.
• Figure 5: Distribution of the four-lepton reconstructed mass for (top) the sum of the $4\mathrm{e}$, $4{\mu}$, and $2\mathrm{e}2{\mu}$ channels, and for (bottom) the sum over all $2\ell2\tau$ channels. Points represent the data, shaded histograms represent the background, and unshaded histogram the signal expectations. The reconstructed masses in $2\ell2\tau$ states are shifted downwards with respect to the true masses by about 30% due to the undetected neutrinos in $\tau$ decays.