CMS-PAS-B2G-24-010

CMS-PAS-B2G-24-010
Search for a new resonance decaying to a pair of Higgs bosons in the $ \mathrm{W}\mathrm{W}\gamma\gamma $ final state in proton-proton collisions at $ \sqrt{s} = 13 \text{TeV} $
CMS Collaboration
2025-10-24

Abstract: A search for a new resonance in a $ \mathrm{W}\mathrm{W}\gamma\gamma $ final state is presented, using CERN LHC proton-proton collision data collected during 2016-2018 by the CMS detector at $ \sqrt{s}= $ 13 TeV, and corresponding to an integrated luminosity of 138 fb$ ^{-1} $. Both the fully hadronic ($ \mathrm{W}\mathrm{W}\to\mathrm{q}\mathrm{q}\mathrm{q}\mathrm{q} $) and semileptonic decay modes ($ \mathrm{W}\mathrm{W}\to\mathrm{q}\mathrm{q}\ell\nu $) of the WW pair are considered. A model-independent search is performed by placing upper limits on the production cross section times branching fraction for a narrow resonance with a mass in the range of 250 GeV to 3 TeV decaying into a pair of Higgs bosons, without assuming any specific scenario of physics beyond the standard model. In addition, the results are interpreted within the context of representative benchmark models, including spin-2 resonances and spin-0 resonances. The observed (expected) 95% confidence level upper limits on the product of the production cross section and branching fraction to Higgs boson pairs are in the range of 30-10700 fb (45-6060 fb) for spin-2 resonances, and 32-11600 fb (48-7220 fb) for spin-0 resonances, depending on the mass of the new resonance.
Links: CDS record (PDF) ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Feynman diagram for BSM X resonance production at LHC via gluon-gluon fusion; X further decays to two SM Higgs bosons with a $ \mathrm{W}\mathrm{W}\gamma\gamma $ final state.
png pdf	Figure 2: Distribution of the resolved PNN scores in the $ m_{\gamma\gamma} $ sideband region. The orange and blue histograms represent the data-driven and simulated diphoton+jets backgrounds, respectively. The filled black markers show the data in the sideband region, and the solid red line indicates the signal, scaled for visibility.
png pdf	Figure 3: Distribution of the boosted PNN scores in the $ m_{\gamma\gamma} $ sideband region. The orange and blue histograms represent the data-driven and simulated diphoton+jets backgrounds, respectively. The filled black markers show the data in the sideband region, and the solid red line indicates the signal, scaled for visibility.
png pdf	Figure 4: The shape of the parametric signal model for each year of simulated data, and for the sum of all years together, is shown. The open squares represent weighted simulation events and the blue line the corresponding model. Also shown is the $ \sigma_{\text{eff}} $ value (half the width of the narrowest interval containing 68.3% of the $ m_{\gamma\gamma} $ distribution) in the grey shaded area. The contribution of the signal model from each year of data taking is illustrated with the dotted lines. The models are shown for the weighted sum of all analysis categories for spin-0 (left) and spin-2 (right) resonances with a mass of 1 TeV.
png pdf	Figure 4-a: The shape of the parametric signal model for each year of simulated data, and for the sum of all years together, is shown. The open squares represent weighted simulation events and the blue line the corresponding model. Also shown is the $ \sigma_{\text{eff}} $ value (half the width of the narrowest interval containing 68.3% of the $ m_{\gamma\gamma} $ distribution) in the grey shaded area. The contribution of the signal model from each year of data taking is illustrated with the dotted lines. The models are shown for the weighted sum of all analysis categories for spin-0 (left) and spin-2 (right) resonances with a mass of 1 TeV.
png pdf	Figure 4-b: The shape of the parametric signal model for each year of simulated data, and for the sum of all years together, is shown. The open squares represent weighted simulation events and the blue line the corresponding model. Also shown is the $ \sigma_{\text{eff}} $ value (half the width of the narrowest interval containing 68.3% of the $ m_{\gamma\gamma} $ distribution) in the grey shaded area. The contribution of the signal model from each year of data taking is illustrated with the dotted lines. The models are shown for the weighted sum of all analysis categories for spin-0 (left) and spin-2 (right) resonances with a mass of 1 TeV.
png pdf	Figure 5: Data points (black) and the signal-plus-background model fit for the sum of all analysis categories are shown. Each analysis category is weighted by S/(S+B), where S and B are the numbers of expected signal and background events, respectively, in a $ \pm $1$\sigma_\mathrm{eff} m_{\gamma\gamma} $ window centred on $ m_{\mathrm{H}} $. The one (green) standard deviation and two (yellow) standard deviation bands show the uncertainties in the background component of the fit. The solid red line shows the resonant HH signal combined with single Higgs and continuum backgrounds, the dashed blue line indicates the single Higgs plus continuum background, and the dashed black line represents the continuum background only. The lower panels show the residuals after subtraction of this background component. The left and right figure correspond to the results obtained when searching for a resonance of $ m_{\mathrm{X}} = $ 500 GeV and 1 TeV, respectively
png pdf	Figure 5-a: Data points (black) and the signal-plus-background model fit for the sum of all analysis categories are shown. Each analysis category is weighted by S/(S+B), where S and B are the numbers of expected signal and background events, respectively, in a $ \pm $1$\sigma_\mathrm{eff} m_{\gamma\gamma} $ window centred on $ m_{\mathrm{H}} $. The one (green) standard deviation and two (yellow) standard deviation bands show the uncertainties in the background component of the fit. The solid red line shows the resonant HH signal combined with single Higgs and continuum backgrounds, the dashed blue line indicates the single Higgs plus continuum background, and the dashed black line represents the continuum background only. The lower panels show the residuals after subtraction of this background component. The left and right figure correspond to the results obtained when searching for a resonance of $ m_{\mathrm{X}} = $ 500 GeV and 1 TeV, respectively
png pdf	Figure 5-b: Data points (black) and the signal-plus-background model fit for the sum of all analysis categories are shown. Each analysis category is weighted by S/(S+B), where S and B are the numbers of expected signal and background events, respectively, in a $ \pm $1$\sigma_\mathrm{eff} m_{\gamma\gamma} $ window centred on $ m_{\mathrm{H}} $. The one (green) standard deviation and two (yellow) standard deviation bands show the uncertainties in the background component of the fit. The solid red line shows the resonant HH signal combined with single Higgs and continuum backgrounds, the dashed blue line indicates the single Higgs plus continuum background, and the dashed black line represents the continuum background only. The lower panels show the residuals after subtraction of this background component. The left and right figure correspond to the results obtained when searching for a resonance of $ m_{\mathrm{X}} = $ 500 GeV and 1 TeV, respectively
png pdf	Figure 6: Upper limits on the production cross section times branching fraction ($ \sigma \times \cal{B} $) for the resonant production of a spin-0 particle decaying into a pair of Higgs bosons, obtained from the analysis of $ \mathrm{g}\mathrm{g} \to \mathrm{X} \to \mathrm{H}\mathrm{H} \to \mathrm{W}\mathrm{W}\gamma\gamma $. Shown are the combined observed limits (solid black line with filled markers), combined expected limits (black dashed line), as well as the expected limits for the boosted category (blue dashed line) and the resolved category (red dashed line).
png pdf	Figure 7: Upper limits on the production cross section times branching fraction ($ \sigma \times \cal{B} $) for the resonant production of a spin-2 particle decaying into a pair of Higgs bosons, obtained from the analysis of $ \mathrm{g}\mathrm{g} \to \mathrm{X} \to \mathrm{H}\mathrm{H} \to \mathrm{W}\mathrm{W}\gamma\gamma $. Shown are the combined observed limits (solid black line with filled markers) and combined expected limits (black dashed line).
png pdf	Figure 8: Upper limits on the production cross section times branching fraction ($ \sigma \times \cal{B} $) for resonant production of a spin-0 particle decaying into a pair of Higgs bosons. The results from this analysis of $ \mathrm{g}\mathrm{g} \to \mathrm{X} \to \mathrm{H}\mathrm{H} \to \mathrm{W}\mathrm{W}\gamma\gamma $ are shown alongside previously published CMS HH results in various final states.
png pdf	Figure 9: Upper limits on the production cross section times branching fraction ($ \sigma \times \cal{B} $) for resonant production of a spin-2 particle decaying into a pair of Higgs bosons. The results from this analysis of $ \mathrm{g}\mathrm{g} \to \mathrm{X} \to \mathrm{H}\mathrm{H} \to \mathrm{W}\mathrm{W}\gamma\gamma $ are shown alongside previously published CMS HH results in various final states.

Tables
png pdf	Table 1: Additional photon requirements for barrel and endcap photons at different ranges of $ R_\mathrm{9} $, intended to mimic the HLT requirements.

Summary

This analysis presents the first search for resonant Higgs boson pair (HH) production in the $ \mathrm{W}\mathrm{W}\gamma\gamma $ final state at CMS. Using data corresponding to an integrated luminosity of 138 fb$ ^{-1} $ collected in pp collisions at a center-of-mass energy of 13 TeV in 2016--2018, we explore various final-state categories, including semileptonic and fully hadronic decay modes of the WW pair. This study extends the search for new resonances decaying into Higgs boson pairs across a wide mass range. The upper limits at 95% confidence level on the product of the production cross section of the spin-0 resonance and its decay branching fraction to HH are observed to be between 32 fb and 11.6 pb, and expected to be between 48 fb and 7220 fb, while for the spin-2 resonance and its decay branching fraction to HH, the limits are observed to be between 30 fb and 10.7 pb, and expected to be between 45 fb and 6060 fb, for a hypothetical resonance with a mass in the range 250--3000 GeV. When deriving the above limits, our signal processes are ($ \mathrm{W}\mathrm{W}\gamma\gamma + \mathrm{b}\overline{\mathrm{b}}\gamma\gamma + \mathrm{Z}\mathrm{Z}\gamma\gamma $), where the corresponding standard model (SM) branching fractions of the $ \mathrm{H} \to \gamma\gamma $ and $ \mathrm{H} \to \mathrm{W}\mathrm{W} $ ($ \mathrm{H} \to \mathrm{b}\overline{\mathrm{b}} $ or $ \mathrm{H} \to \mathrm{Z}\mathrm{Z} $) are assumed. The upper limits placed on the production cross sections of such resonant states provide valuable constraints on various beyond-SM (BSM) scenarios, including those with extended Higgs sectors. These results contribute to our understanding of the Higgs mechanism and the exploration of new physics beyond the SM. The search for BSM Higgs bosons remains a vibrant area of research, and this work lays the foundation for future studies aimed at exploring possible new resonances beyond the SM, including both scalar and spin-2 interpretations.

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