CMSHIG20002 ; CERNEP2024088  
Search for a standard modellike Higgs boson in the mass range between 70 and 110 GeV in the diphoton final state in protonproton collisions at $ \sqrt{s}= $ 13 TeV  
CMS Collaboration  
28 May 2024  
Submitted to Phys. Lett. B  
Abstract: The results of a search for a standard modellike Higgs boson decaying into two photons in the mass range between 70 and 110 GeV are presented. The analysis uses the data set collected by the CMS experiment in protonproton collisions at $ \sqrt{s}= $ 13 TeV corresponding to integrated luminosities of 36.3 fb$ ^{1} $, 41.5 fb$ ^{1} $ and 54.4 fb$ ^{1} $ during the 2016, 2017, and 2018 LHC running periods, respectively. No significant excess over the background expectation is observed and 95% confidence level upper limits are set on the product of the cross section and branching fraction for decays of an additional Higgs boson into two photons. The maximum deviation with respect to the background is seen for a mass hypothesis of 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. The observed upper limit ranges from 15 to 73 fb.  
Links: eprint arXiv:2405.18149 [hepex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; 
Figures & Tables  Summary  Additional Figures  References  CMS Publications 

Figures  
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Figure 1:
Full parametrized signal shape, integrated over all event classes, in simulated signal events with $ m_{\mathrm{H}}= $ 90 GeV for 2016 (upper left), 2017 (upper right), and 2018 (lower). The open points are the weighted MC events and the blue lines the corresponding parametric models. Also shown are the $ \sigma_{\text{eff}} $ values and the shaded region limited by $ {\pm}\sigma_{\text{eff}} $, along with the FWHM values, indicated by the position of the arrows on each distribution. 
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Figure 1a:
Full parametrized signal shape, integrated over all event classes, in simulated signal events with $ m_{\mathrm{H}}= $ 90 GeV for 2016 (upper left), 2017 (upper right), and 2018 (lower). The open points are the weighted MC events and the blue lines the corresponding parametric models. Also shown are the $ \sigma_{\text{eff}} $ values and the shaded region limited by $ {\pm}\sigma_{\text{eff}} $, along with the FWHM values, indicated by the position of the arrows on each distribution. 
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Figure 1b:
Full parametrized signal shape, integrated over all event classes, in simulated signal events with $ m_{\mathrm{H}}= $ 90 GeV for 2016 (upper left), 2017 (upper right), and 2018 (lower). The open points are the weighted MC events and the blue lines the corresponding parametric models. Also shown are the $ \sigma_{\text{eff}} $ values and the shaded region limited by $ {\pm}\sigma_{\text{eff}} $, along with the FWHM values, indicated by the position of the arrows on each distribution. 
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Figure 1c:
Full parametrized signal shape, integrated over all event classes, in simulated signal events with $ m_{\mathrm{H}}= $ 90 GeV for 2016 (upper left), 2017 (upper right), and 2018 (lower). The open points are the weighted MC events and the blue lines the corresponding parametric models. Also shown are the $ \sigma_{\text{eff}} $ values and the shaded region limited by $ {\pm}\sigma_{\text{eff}} $, along with the FWHM values, indicated by the position of the arrows on each distribution. 
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Figure 2:
Background model fits using the chosen background model parametrization to the 2016 data in the three event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 2a:
Background model fits using the chosen background model parametrization to the 2016 data in the three event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 2b:
Background model fits using the chosen background model parametrization to the 2016 data in the three event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 2c:
Background model fits using the chosen background model parametrization to the 2016 data in the three event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 3:
Background model fits using the chosen background model parametrization to the 2017 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 3a:
Background model fits using the chosen background model parametrization to the 2017 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 3b:
Background model fits using the chosen background model parametrization to the 2017 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 3c:
Background model fits using the chosen background model parametrization to the 2017 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 3d:
Background model fits using the chosen background model parametrization to the 2017 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 4:
Background model fits using the chosen background model parametrization to the 2018 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 4a:
Background model fits using the chosen background model parametrization to the 2018 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 4b:
Background model fits using the chosen background model parametrization to the 2018 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 4c:
Background model fits using the chosen background model parametrization to the 2018 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 4d:
Background model fits using the chosen background model parametrization to the 2018 data in the four event classes. The corresponding signal model for each class and $ m_{\mathrm{H}}= $ 90 GeV, multiplied by 10, is also shown. The one and two$ \sigma $ bands reflect the uncertainty in the background model normalization associated with the statistical uncertainties of the fits, and are shown for illustration purposes only. The difference between the data and the background model is shown in the lower panels. 
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Figure 5:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ {\pm}$1$\sigma $ and $ {\pm}$2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. The limit is shown relative to the expected SMlike value (left). The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty [67] (right). 
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Figure 5a:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ {\pm}$1$\sigma $ and $ {\pm}$2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. The limit is shown relative to the expected SMlike value (left). The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty [67] (right). 
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Figure 5b:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ {\pm}$1$\sigma $ and $ {\pm}$2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. The limit is shown relative to the expected SMlike value (left). The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty [67] (right). 
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Figure 6:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, for the ggH plus $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $ (upper left) and VBF plus VH (upper right) processes, and assuming 100% production via the VBF (lower left) or VH (lower right) processes, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1$\sigma $ and $ \pm $2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Figure 6a:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, for the ggH plus $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $ (upper left) and VBF plus VH (upper right) processes, and assuming 100% production via the VBF (lower left) or VH (lower right) processes, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1$\sigma $ and $ \pm $2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Figure 6b:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, for the ggH plus $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $ (upper left) and VBF plus VH (upper right) processes, and assuming 100% production via the VBF (lower left) or VH (lower right) processes, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1$\sigma $ and $ \pm $2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Figure 6c:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, for the ggH plus $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $ (upper left) and VBF plus VH (upper right) processes, and assuming 100% production via the VBF (lower left) or VH (lower right) processes, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1$\sigma $ and $ \pm $2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Figure 6d:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, for the ggH plus $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $ (upper left) and VBF plus VH (upper right) processes, and assuming 100% production via the VBF (lower left) or VH (lower right) processes, from the statistical combination of the 2016, 2017, and 2018 data sets. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1$\sigma $ and $ \pm $2$\sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Figure 7:
The observed local $ p $values for an additional SMlike Higgs boson as a function of $ m_{\mathrm{H}} $, from the analysis of the data from 2016, 2017, 2018, and their combination. 
Tables  
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Table 1:
Families and orders of functions chosen as best fit when summed with the DCB + exponential function, by year and by event class, in the case of backgroundonly fits. The DCB + exponential fractions for these models in the range 85 $ < m_{\gamma\gamma} < $ 95 GeV are also shown. 
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Table 2:
The expected number of SMlike Higgs boson signal events ($ m_{\mathrm{H}}= $ 90 GeV) per event class and the corresponding percentage breakdown per production process, for the 2016, 2017, and 2018 data. The values of $ \sigma_{\text{eff}} $ and $ \sigma_{\text{HM}} $ are also shown, along with the number of background events (``Bkg.'') per GeV estimated from the backgroundonly fit to the data, that includes the number, shown separately, from the DY process (``DY Bkg.''), in a $ \sigma_{\text{eff}} $ window centered on $ m_{\mathrm{H}}= $ 90 GeV. 
Summary 
A search for an additional, SMlike, lowmass Higgs boson decaying into two photons has been presented. It is based upon data samples corresponding to an integrated luminosity of 132 fb$ ^{1} $ collected in pp collisions at a centerofmass energy of 13 TeV in 20162018. The search is performed in a mass range between 70 and 110 GeV. The expected and observed 95% CL upper limits on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson as well as the expected and observed local $ p $values are presented. The observed upper limit on the product of the production cross section and branching fraction for the full data set ranges from 15 to 73 fb. The results of the statistical combination of the analyses of the three data sets show no significant excess over the background expectation. The maximum deviation with respect to the background is seen for a mass hypothesis of 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. 
Additional Figures  
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Additional Figure 1:
Signal efficiency $ \times $ acceptance for the analysis of the 2016 data set, as a function of mass hypothesis. 
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Additional Figure 2:
Signal efficiency $ \times $ acceptance for the analysis of the 2017 data set, as a function of mass hypothesis. 
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Additional Figure 3:
Signal efficiency $ \times $ acceptance for the analysis of the 2018 data set, as a function of mass hypothesis. 
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Additional Figure 4:
Distributions of the variable $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) $ for simulated surviving DrellYan events (red) and simulated signal events corresponding to an SMlike Higgs boson with $ m_{H} $ = 90 GeV produced via the ggH process (black), with both distributions normalized to 1, for the analysis of the 2018 data set. The events are required to have survived the analysis preselection, the pixel detectorbased electron veto, and have diphoton BDT classifier values greater than 0.364. This variable, corresponding to the natural logarithm of the sum of the squares of transverse momenta of all tracks associated with the chosen diphoton vertex, is used to suppress the surviving DrellYan background. For the simulated DrellYan events, the peak at $ \sim $8.3 reflects the contributions of the two electron tracks, while the peak at $ \sim $7.6 that of one electron track, the other either being out of the detector acceptance or not reconstructed due to significant bremsstrahlung. The peak at $ \sim $5 corresponds to the case where neither of the electron tracks is reconstructed, similar to that of signal events where the main contributions are from tracks from pileup and the underlying event. 
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Additional Figure 5:
Twodimensional distribution of $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) $ versus diphoton transverse momentum ($ p_{\mathrm{T}}^{\gamma\gamma}/\mathrm{GeV} $) for simulated signal events corresponding to an SMlike Higgs boson with $ m_{H} $ = 90 GeV produced via the ggH process, with the distribution normalized to 1, for the analysis of the 2018 data set. The events are required to have survived the analysis preselection, the pixel detectorbased electron veto, and have diphoton BDT classifier values greater than 0.364. The upper limit on $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) $, $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) = 0.016p_{\mathrm{T}}^{\gamma\gamma}/\mathrm{GeV} + $ 6.0, is shown as the white line. 
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Additional Figure 6:
Twodimensional distribution of $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) $ versus diphoton transverse momentum ($ p_{\mathrm{T}}^{\gamma\gamma}/\mathrm{GeV} $) for simulated surviving DrellYan events, with the distribution normalized to 1, for the analysis of the 2018 data set. The events are required to have survived the analysis preselection, the pixel detectorbased electron veto, and have diphoton BDT classifier values greater than 0.364. The upper limit on $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) $, $\ln(\Sigma p_{\mathrm{T}}^{2}/\mathrm{GeV}^{2}) = 0.016p_{\mathrm{T}}^{\gamma\gamma}/\mathrm{GeV} + $ 6.0, is shown as the white line. 
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Additional Figure 7:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons relative to the value expected for an additional SMlike Higgs boson, from the analysis of the 2016 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Additional Figure 8:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional SMlike Higgs boson, from the analysis of the 2016 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty. 
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Additional Figure 9:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons relative to the value expected for an additional SMlike Higgs boson, from the analysis of the 2017 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Additional Figure 10:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional SMlike Higgs boson, from the analysis of the 2017 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty. 
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Additional Figure 11:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons relative to the value expected for an additional SMlike Higgs boson, from the analysis of the 2018 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. 
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Additional Figure 12:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional SMlike Higgs boson, from the analysis of the 2018 data set. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The corresponding theoretical prediction for the product of the cross section and branching fraction into two photons for an additional SMlike Higgs boson is shown as a solid line with a hatched band, indicating its uncertainty. 
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Additional Figure 13:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons for an additional SMlike Higgs boson, from the analysis of the combined data from 2016, 2017, and 2018. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The corresponding theoretical predictions for the product of the cross section and branching fraction into two photons are shown as a solid blue line with a hatched red band indicating its uncertainty for an additional SMlike Higgs boson ($ \sigma_{SM} \times B $), and a solid red line with a hatched blue band indicating its uncertainty for a Higgs boson in the Fermiophobic model $ (\sigma \times B)_{FP} $. 
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Additional Figure 14:
Values of the signal strength $ \widehat{\mu} $ measured individually for the eleven event classes in the analysis of the combined data from 2016, 2017, and 2018, and the overall combined value, with $ m_H $ fixed to that of the largest local pvalue excess. The horizontal bars indicate $ \pm 1\sigma $ uncertainties in the values, and the vertical line and band indicate the value of the combined $ \widehat{\mu} $ in the fit to the data and its uncertainty. The $ \chi^2 $ probability of the values for the eleven event classes being compatible with the overall bestfit signal strength is 68%. 
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Additional Figure 15:
Values of the signal strength $ \widehat{\mu} $ measured individually for each year, and the overall combined value, with $ m_H $ fixed to that of the largest local pvalue excess. The horizontal bars indicate $ \pm 1\sigma $ uncertainties in the values, and the vertical line and band indicate the value of the combined $ \widehat{\mu} $ in the fit to the data and its uncertainty. The $ \chi^2 $ probability of the values for the three years being compatible with the overall bestfit signal strength is 6%. 
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Additional Figure 16:
Events in all classes of the combined 13$ \mathrm{TeV} $ data set, binned as a function of $ m_{\gamma\gamma} $, together with the result of a fit of the signalplusbackground model, under a mass hypothesis of 95.4 GeV. The one and two$ \sigma $ uncertainty bands shown for the background component of the fit include the uncertainty due to the choice of fit function and the uncertainty in the fitted parameters. The distribution of the residual data after subtracting the fitted background component is shown in the lower panel. 
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Additional Figure 17:
Events in all classes of the combined 13 TeV data set, binned as a function of $ m_{\gamma\gamma} $, together with the result of a fit of the signalplusbackground model, under a mass hypothesis of 95.4 GeV. Each event is weighted by the ratio S/(S+B) for its event class, where S and B are the numbers of expected signal and background events, respectively, in a $ \pm 1\sigma_{\text{eff}} m_{\gamma\gamma} $ window centred on $ m_{\mathrm{H}} $. The one and two$ \sigma $ uncertainty bands shown for the background component of the fit include the uncertainty due to the choice of fit function and the uncertainty in the fitted parameters. The distribution of the residual weighted data after subtracting the fitted background component is shown in the lower panel. 
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Additional Figure 18:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f \times (\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.1, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 17 to 82 fb. 
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Additional Figure 19:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.2, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 16 to 80 fb. 
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Additional Figure 20:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.3, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 16 to 79 fb. 
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Additional Figure 21:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.4, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 16 to 77 fb. 
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Additional Figure 22:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.5, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 15 to 74 fb. 
png pdf 
Additional Figure 23:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.6, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 14 to 70 fb. 
png pdf 
Additional Figure 24:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.7, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 13 to 64 fb. 
png pdf 
Additional Figure 25:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.8, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 12 to 56 fb. 
png pdf 
Additional Figure 26:
Expected and observed exclusion limits (95% CL, in the asymptotic approximation) on the product of the production cross section and branching fraction into two photons, for an additional Higgs boson from the analysis of the combined data from 2016, 2017 and 2018, with assumption of the total cross section $ \sigma = (1f)\times(\sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} + \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}}) + f\times(\sigma_{SM}^{\mathrm{V}\mathrm{H}} + \sigma_{SM}^{VBF}) $ with the additional parameter $ f $ = 0.9, where $ \sigma_{SM}^{\mathrm{g}\mathrm{g}\mathrm{H}} $, $ \sigma_{SM}^{{\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}} $, $ \sigma_{SM}^{\mathrm{V}\mathrm{H}} $ and $ \sigma_{SM}^{VBF} $ are the SMlike cross sections of the ggH, $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H} $, VH and VBF production modes. The inner and outer bands indicate the regions containing the distribution of limits located within $ \pm $1 and 2$ \sigma $, respectively, of the expectation under the backgroundonly hypothesis. The observed upper limit ranges from 10 to 45 fb. 
png pdf 
Additional Figure 27:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 70 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.22, 0.20). 
png pdf 
Additional Figure 28:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 75 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.14, 0.22). 
png pdf 
Additional Figure 29:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 80 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.0, 0.0). 
png pdf 
Additional Figure 30:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 85 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.0, 0.0). 
png pdf 
Additional Figure 31:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 90 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.28, 0.0). 
png pdf 
Additional Figure 32:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 95.4 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.47, 0.05). 
png pdf 
Additional Figure 33:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 100 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.0, 0.39). 
png pdf 
Additional Figure 34:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 105 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.03, 0.0). 
png pdf 
Additional Figure 35:
Maximum likelihood estimates, and 68 and 95% confidence level contours obtained from scans of the signal likelihood as a function of $ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $ versus $ \mu_{VBF} $ for $ m_{H} $ = 110 GeV, when considering only ggH and VBF production modes. The bestfit result is ($ \mu_{ \mathrm{g}\mathrm{g}\mathrm{H} } $, $ \mu_{VBF} $) = (0.0, 0.0). 
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