CMSB2G21003 ; CERNEP2022034  
Search for a massive scalar resonance decaying to a light scalar and a Higgs boson in the four b quarks final state with boosted topology  
CMS Collaboration  
26 April 2022  
Phys. Lett. B 842 (2023) 137392  
Abstract: We search for new massive scalar particles X and Y through the resonant process ${\mathrm{X}\to\mathrm{Y}\mathrm{H}\to\mathrm{b\bar{b}}\mathrm{b\bar{b}}} $, where H is the standard model Higgs boson. Data from CERN LHC protonproton collisions are used, collected at a centreofmass energy of 13 TeV in 20162018 and corresponding to an integrated luminosity of 138 fb$^{1}$. The search is performed in mass ranges of 0.94 TeV for X and 60600 GeV for Y, where both Y and H are reconstructed as Lorentzboosted single largearea jets. The results are interpreted in the context of the nexttominimal supersymmetric standard model and also in an extension of the standard model with two additional singlet scalar fields. The 95% confidence level upper limits for the production cross section vary between 0.1 and 150 fb depending on the X and Y masses, and represent a significant improvement over results from previous searches.  
Links: eprint arXiv:2204.12413 [hepex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; 
Figures  
png pdf 
Figure 1:
Simulated ParticleNet score distributions of the H and the Y candidate jets for a signal with $ {M_{\mathrm{X}}} = $ 1600 GeV and $ {M_{\mathrm{Y}}} = $ 90 GeV (filled squares) and the multijets background (open circles). The grid lines show the different event categories defined using the ParticleNet scores of the two jets. A description of the regions is given in Table 1 and in the text. 
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Figure 2:
The ${M_{\mathrm {J}}^{\mathrm{Y}}}$ (left) and ${M_{\mathrm {JJ}}}$ (right) distributions for the number of observed events (black markers) compared with the estimated backgrounds (filled histograms) and their uncertainties (hatched areas) in SR1. The distributions expected from the signal under three ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$ hypotheses and assuming a cross section of 1 fb are also shown. The lower panels show the "Pulls'' defined as observed events$$expected events$/\sqrt {\smash [b]{{\sigma _{\text {obs}}} ^{2}  {\sigma _{\text {exp}}} ^{2}}}$, where ${\sigma _{\text {obs}}}$ and ${\sigma _{\text {exp}}}$ are the statistical and total uncertainties in the observation and the background estimation, respectively. The minus sign accounts for the correlation between data and the datadriven estimation. 
png pdf 
Figure 2a:
The ${M_{\mathrm {J}}^{\mathrm{Y}}}$ distribution for the number of observed events (black markers) compared with the estimated backgrounds (filled histograms) and their uncertainties (hatched areas) in SR1. The distributions expected from the signal under three ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$ hypotheses and assuming a cross section of 1 fb are also shown. The lower panel shows the "Pulls'' defined as observed events$$expected events$/\sqrt {\smash [b]{{\sigma _{\text {obs}}} ^{2}  {\sigma _{\text {exp}}} ^{2}}}$, where ${\sigma _{\text {obs}}}$ and ${\sigma _{\text {exp}}}$ are the statistical and total uncertainties in the observation and the background estimation, respectively. The minus sign accounts for the correlation between data and the datadriven estimation. 
png pdf 
Figure 2b:
The ${M_{\mathrm {JJ}}}$ distribution for the number of observed events (black markers) compared with the estimated backgrounds (filled histograms) and their uncertainties (hatched areas) in SR1. The distributions expected from the signal under three ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$ hypotheses and assuming a cross section of 1 fb are also shown. The lower panel shows the "Pulls'' defined as observed events$$expected events$/\sqrt {\smash [b]{{\sigma _{\text {obs}}} ^{2}  {\sigma _{\text {exp}}} ^{2}}}$, where ${\sigma _{\text {obs}}}$ and ${\sigma _{\text {exp}}}$ are the statistical and total uncertainties in the observation and the background estimation, respectively. The minus sign accounts for the correlation between data and the datadriven estimation. 
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Figure 3:
The softdrop mass distributions of the top quark candidate jets in the 2018 jets+lepton category, in the tight ParticleNet region, after the joint fit in the alljets and jets+lepton categories. The observed data (black markers) and the postfit estimate (filled histograms) are shown for the three jet categories. The lower panels show the ``Pulls'' defined as (observed events $$ expected events) $ /\sqrt{\smash[b]{\sigma_{\text{obs}}^{2} + \sigma_{\text{exp}}^{2}}} $, where $ \sigma_{\text{obs}} $ and $ \sigma_{\text{exp}} $ are the total uncertainties in the observation and the background estimation, respectively. 
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Figure 4:
The 95% confidence level expected (left) and observed (right) upper limits on $\sigma ({\mathrm{p}} {\mathrm{p}} \to {\mathrm{X} \to \mathrm{Y} \mathrm{H} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}}})$ for different values of ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$. The areas within the red and black contours represent the regions where the cross sections predicted by NMSSM and TRSM, respectively, are larger than the experimental limits. The areas within the dashed and dotted contours on the left show the excluded masses at $$ standard deviation from the expected limits. 
png pdf 
Figure 4a:
The 95% confidence level expected upper limits on $\sigma ({\mathrm{p}} {\mathrm{p}} \to {\mathrm{X} \to \mathrm{Y} \mathrm{H} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}}})$ for different values of ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$. The areas within the red and black contours represent the regions where the cross sections predicted by NMSSM and TRSM, respectively, are larger than the experimental limits. The areas within the dashed and dotted contours on the left show the excluded masses at $$ standard deviation from the expected limits. 
png pdf 
Figure 4b:
The 95% confidence level observed upper limits on $\sigma ({\mathrm{p}} {\mathrm{p}} \to {\mathrm{X} \to \mathrm{Y} \mathrm{H} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}}})$ for different values of ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$. The areas within the red and black contours represent the regions where the cross sections predicted by NMSSM and TRSM, respectively, are larger than the experimental limits. The areas within the dashed and dotted contours on the left show the excluded masses at $$ standard deviation from the expected limits. 
Summary 
A search for massive scalar resonances X and Y, where X decays to Y and the standard model Higgs boson H, has been performed using protonproton collision data collected at the LHC by the CMS detector between 2016 and 2018, and corresponding to an integrated luminosity of 138 fb$^{1}$. Events are selected using jet substructure and neural network based boosted $\mathrm{H}/ \mathrm{Y} \to \mathrm{b\bar{b}}$ identification algorithms. Upper limits at 95% confidence level are set on the cross section of the process ${\mathrm{p}}{\mathrm{p}} \to {\mathrm{X}\to\mathrm{Y}\mathrm{H}\to\mathrm{b\bar{b}}\mathrm{b\bar{b}}} $ for assumed masses of X in the range 0.94 TeV and Y between 60600 GeV. The expected and observed cross section limits for the considered process, set between 0.1 and 150 fb, are the most stringent to date over much of the explored mass range. These limits are interpreted as exclusion of possible ${M_{\mathrm{X}}}$ and ${M_{\mathrm{Y}}}$ within the frameworks of the nexttominimal supersymmetric model and the tworealscalarsinglet extension of the standard model. 
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