CMS-PAS-B2G-20-004

CMS-PAS-B2G-20-004
Search for resonant Higgs boson pair production in four b quark final state using large-area jets in proton-proton collisions at $\sqrt{s}= $ 13 TeV
CMS Collaboration
July 2021

Abstract: A search is presented for pair production of the standard model Higgs boson using data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected by the CMS experiment at the CERN LHC in 2016-2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The final state consists of two b quark-antiquark pairs. The search is conducted in the region of phase space where at least one of the pairs is highly Lorentz-boosted and is reconstructed as a single large-area jet. The other pair may be either similarly boosted or resolved, the latter reconstructed using two b-tagged jets. The data was found to be consistent with the measured standard model processes. Limits in the range 9.74-0.29 fb and 4.94-0.19 fb were set on the product of the cross sections and the branching fractions of the spin-0 radion and the spin-2 bulk graviton with a mass of 1-3 TeV, respectively, in the context of warped extradimensional models.
Links: CDS record (PDF) ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Slices of two-dimensional distributions of observed events and the post-fit templates in the LL pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV. For this and following figures, the value of $\sigma $ in the lower panel is $\sigma = \sqrt {\sigma _{bkg}^2 + \sigma _{data}^2}$.
png pdf	Figure 1-a: Slices of two-dimensional distributions of observed events and the post-fit templates in the LL pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV. For this and following figures, the value of $\sigma $ in the lower panel is $\sigma = \sqrt {\sigma _{bkg}^2 + \sigma _{data}^2}$.
png pdf	Figure 1-b: Slices of two-dimensional distributions of observed events and the post-fit templates in the LL pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV. For this and following figures, the value of $\sigma $ in the lower panel is $\sigma = \sqrt {\sigma _{bkg}^2 + \sigma _{data}^2}$.
png pdf	Figure 2: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 2-a: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 2-b: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 3: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 3-a: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 3-b: Slices of two-dimensional distributions of observed events and the post-fit templates in the TT pass region, projected onto the $ {m_{\text {J}}} $ (left) and $ {m_\text {red}} $ (right) axes, including expected radion signal at 1500 GeV.
png pdf	Figure 4: Upper limits at 95% confidence level on $\sigma ({\mathrm{p}} {\mathrm{p}} \to \mathrm{X}) \mathcal {B}(\mathrm{X} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}})$ for the narrow spin-0 radion (left) and the spin-2 bulk graviton (right) models. The predicted theoretical cross sections for the narrow radion and bulk graviton are also shown.
png pdf	Figure 4-a: Upper limits at 95% confidence level on $\sigma ({\mathrm{p}} {\mathrm{p}} \to \mathrm{X}) \mathcal {B}(\mathrm{X} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}})$ for the narrow spin-0 radion (left) and the spin-2 bulk graviton (right) models. The predicted theoretical cross sections for the narrow radion and bulk graviton are also shown.
png pdf	Figure 4-b: Upper limits at 95% confidence level on $\sigma ({\mathrm{p}} {\mathrm{p}} \to \mathrm{X}) \mathcal {B}(\mathrm{X} \to \mathrm{b} {}\mathrm{\bar{b}} \mathrm{b} {}\mathrm{\bar{b}})$ for the narrow spin-0 radion (left) and the spin-2 bulk graviton (right) models. The predicted theoretical cross sections for the narrow radion and bulk graviton are also shown.

Tables
png pdf	Table 1: Event selection for the fully-merged topology.
png pdf	Table 2: Event selection for the semi-resolved topology.
png pdf	Table 3: Summary of the ranges of systematic uncertainties in the signal and background yields, for the combined fit of all ten regions for the radion resonance at 1500 GeV.
png pdf	Table 4: Radion observed 95% CL exclusion limits.
png pdf	Table 5: Graviton observed 95% CL exclusion limits.

Summary

A search is presented for the pair production of standard model Higgs bosons (HH), both decaying to a bottom quark-antiquark pair ($\mathrm{b\bar{b}}$), using data from proton-proton collisions at a centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb$^{-1}$. The search is conducted in the region of phase space where at least one of the Higgs bosons has a large Lorentz boost, so that the $\mathrm{H}\to\mathrm{b\bar{b}}$ decay products are collimated to form a single H jet. The search combines events with one H jet plus two b jets with events having two H jets, thus adding sensitivity to the previous analysis [32].

The results of the search are compared with predictions for the resonant production of a narrow Kaluza-Klein bulk graviton and a narrow radion in warped extradimensional models. The search is also sensitive to several beyond standard model non-resonant HH production scenarios. Such cases may arise either when an off-shell massive resonance produced in proton-proton collisions decays to HH, or through beyond standard model effects in the Higgs boson coupling parameters. The results are interpreted in terms of upper limits on the product of the cross section for the respective signal processes and the branching fraction to $\mathrm{H}\mathrm{H} \to \mathrm{b\bar{b}}\mathrm{b\bar{b}}$, at 95% confidence level.

The upper limits range from 4.94 to 0.19 fb} for the bulk graviton and from 9.74 to 0.29 fb for the radion for the mass range 1-3 TeV.

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