CMS-PAS-HIG-21-002

CMS-PAS-HIG-21-002
Search for Higgs boson pairs decaying to WWWW, WW $\tau\tau$ , and $\tau\tau\tau\tau$ in proton-proton collisions at $\sqrt{s} =$ 13 TeV
CMS Collaboration
January 2022

Abstract: The results of a search for Higgs boson pair (HH) production in the WWWW, WW $\tau \tau$ , and $\tau\tau\tau\tau$ decay modes are presented. The search uses proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb $^{-1}$ . The analyzed events contain two, three, or four reconstructed leptons, including electrons, muons, and hadronically decaying tau leptons. No evidence for a signal is found in the data, and upper limits are set on the cross section for nonresonant HH production, as well as resonant production in which a new heavy particle decays to a pair of Higgs bosons. For nonresonant HH production, the observed (expected) upper limit on the cross section at 95% confidence level (CL) is 21.8 (19.6) times the standard model (SM) prediction. The ratio of the trilinear Higgs boson self-coupling to its value in the SM is constrained to be between -7.0 and 11.2 at 95% CL, and limits are set on a variety of new-physics models using an effective field theory approach. The observed (expected) limits on the cross section for resonant HH production range from 0.18 to 0.90 (0.08 to 1.07) pb at 95% CL for new heavy-particle masses from 250 to 1000 GeV.
Links: CDS record (PDF) ; Physics Briefing ; CADI line (restricted) ; These preliminary results are superseded in this paper, JHEP 07 (2023) 095. The superseded preliminary plots can be found here.

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 1-a: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 1-b: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 1-c: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 1-d: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 1-e: LO Feynman diagrams for SM nonresonant HH production via gluon fusion (a, b) and via vector boson fusion (c, d, e).
png pdf	Figure 2: LO Feynman diagrams for nonresonant HH production via gluon fusion in an effective field theory approach where loop-mediated contact interactions between (a) two gluons and one Higgs boson, (b) two gluons and two Higgs bosons, and (c) two top quarks and two Higgs bosons are parametrized by three effective couplings: ${\text {c}_{{\mathrm{g}}}}$ , ${\text {c}_{2 {\mathrm{g}}}}$ , and ${\text {c}_{2}}$ .
png pdf	Figure 2-a: LO Feynman diagrams for nonresonant HH production via gluon fusion in an effective field theory approach where loop-mediated contact interactions between (a) two gluons and one Higgs boson, (b) two gluons and two Higgs bosons, and (c) two top quarks and two Higgs bosons are parametrized by three effective couplings: ${\text {c}_{{\mathrm{g}}}}$ , ${\text {c}_{2 {\mathrm{g}}}}$ , and ${\text {c}_{2}}$ .
png pdf	Figure 2-b: LO Feynman diagrams for nonresonant HH production via gluon fusion in an effective field theory approach where loop-mediated contact interactions between (a) two gluons and one Higgs boson, (b) two gluons and two Higgs bosons, and (c) two top quarks and two Higgs bosons are parametrized by three effective couplings: ${\text {c}_{{\mathrm{g}}}}$ , ${\text {c}_{2 {\mathrm{g}}}}$ , and ${\text {c}_{2}}$ .
png pdf	Figure 2-c: LO Feynman diagrams for nonresonant HH production via gluon fusion in an effective field theory approach where loop-mediated contact interactions between (a) two gluons and one Higgs boson, (b) two gluons and two Higgs bosons, and (c) two top quarks and two Higgs bosons are parametrized by three effective couplings: ${\text {c}_{{\mathrm{g}}}}$ , ${\text {c}_{2 {\mathrm{g}}}}$ , and ${\text {c}_{2}}$ .
png pdf	Figure 3: LO Feynman diagram for resonant HH production.
png pdf	Figure 4: Distribution in the observable ${m_\text {T}}$ in the 3 ${\ell}$ WZ CR (left) and in the observable $m_{4 {\ell}}$ in the 4 ${\ell}$ ZZ CR (right). The distributions expected for the WZ and ZZ as well as for other background processes are shown for the values of nuisance parameters obtained from the ML fit described in Section 9.
png pdf	Figure 4-a: Distribution in the observable ${m_\text {T}}$ in the 3 ${\ell}$ WZ CR (left) and in the observable $m_{4 {\ell}}$ in the 4 ${\ell}$ ZZ CR (right). The distributions expected for the WZ and ZZ as well as for other background processes are shown for the values of nuisance parameters obtained from the ML fit described in Section 9.
png pdf	Figure 4-b: Distribution in the observable ${m_\text {T}}$ in the 3 ${\ell}$ WZ CR (left) and in the observable $m_{4 {\ell}}$ in the 4 ${\ell}$ ZZ CR (right). The distributions expected for the WZ and ZZ as well as for other background processes are shown for the values of nuisance parameters obtained from the ML fit described in Section 9.
png pdf	Figure 5: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 2 ${\ell}$ ss (top left), 3 ${\ell}$ (top right), and 4 ${\ell}$ (bottom) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 5-a: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 2 ${\ell}$ ss (top left), 3 ${\ell}$ (top right), and 4 ${\ell}$ (bottom) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 5-b: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 2 ${\ell}$ ss (top left), 3 ${\ell}$ (top right), and 4 ${\ell}$ (bottom) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 5-c: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 2 ${\ell}$ ss (top left), 3 ${\ell}$ (top right), and 4 ${\ell}$ (bottom) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 6: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 3 ${\ell}$ + 1 ${\tau _{\text {h}}}$ (top left), 2 ${\ell}$ + 2 ${\tau _{\text {h}}}$ (top right), 1 ${\ell}$ + 3 ${\tau _{\text {h}}}$ (bottom left), and 4 ${\tau _{\text {h}}}$ (bottom right) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 6-a: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 3 ${\ell}$ + 1 ${\tau _{\text {h}}}$ (top left), 2 ${\ell}$ + 2 ${\tau _{\text {h}}}$ (top right), 1 ${\ell}$ + 3 ${\tau _{\text {h}}}$ (bottom left), and 4 ${\tau _{\text {h}}}$ (bottom right) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 6-b: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 3 ${\ell}$ + 1 ${\tau _{\text {h}}}$ (top left), 2 ${\ell}$ + 2 ${\tau _{\text {h}}}$ (top right), 1 ${\ell}$ + 3 ${\tau _{\text {h}}}$ (bottom left), and 4 ${\tau _{\text {h}}}$ (bottom right) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 6-c: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 3 ${\ell}$ + 1 ${\tau _{\text {h}}}$ (top left), 2 ${\ell}$ + 2 ${\tau _{\text {h}}}$ (top right), 1 ${\ell}$ + 3 ${\tau _{\text {h}}}$ (bottom left), and 4 ${\tau _{\text {h}}}$ (bottom right) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 6-d: Distribution in the output of the BDT for nonresonant HH production used in the $\kappa$ scans (BM7 from Ref. [24]) for the 3 ${\ell}$ + 1 ${\tau _{\text {h}}}$ (top left), 2 ${\ell}$ + 2 ${\tau _{\text {h}}}$ (top right), 1 ${\ell}$ + 3 ${\tau _{\text {h}}}$ (bottom left), and 4 ${\tau _{\text {h}}}$ (bottom right) categories. The SM HH signal is shown for a cross section amounting to $30$ times the value predicted in the SM. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value of the HH production rate amounts to $\hat{\mu} =$ 1.96 $^{+10.57}_{-9.98}$ times the rate expected in the SM.
png pdf	Figure 7: Observed and expected 95% CL upper limits on the SM HH production cross section, obtained for both individual search categories and from a simultaneous fit of all seven search categories combined.
png pdf	Figure 8: Observed and expected 95% CL upper limits on the HH production cross section as a function of the Higgs boson self-coupling strength modifier ${\kappa _{\lambda}}$ . All Higgs boson couplings other than $\lambda$ are assumed to have the values predicted in the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately. Overlaid on the left is a curve in red representing the predicted HH production cross section.
png pdf	Figure 8-a: Observed and expected 95% CL upper limits on the HH production cross section as a function of the Higgs boson self-coupling strength modifier ${\kappa _{\lambda}}$ . All Higgs boson couplings other than $\lambda$ are assumed to have the values predicted in the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately. Overlaid on the left is a curve in red representing the predicted HH production cross section.
png pdf	Figure 8-b: Observed and expected 95% CL upper limits on the HH production cross section as a function of the Higgs boson self-coupling strength modifier ${\kappa _{\lambda}}$ . All Higgs boson couplings other than $\lambda$ are assumed to have the values predicted in the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately. Overlaid on the left is a curve in red representing the predicted HH production cross section.
png pdf	Figure 9: Observed and expected 95% CL upper limits on the HH production cross section for twelve benchmark scenarios from Ref. [24], the additional benchmark scenario 8a from Ref. [62], and for the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 9-a: Observed and expected 95% CL upper limits on the HH production cross section for twelve benchmark scenarios from Ref. [24], the additional benchmark scenario 8a from Ref. [62], and for the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 9-b: Observed and expected 95% CL upper limits on the HH production cross section for twelve benchmark scenarios from Ref. [24], the additional benchmark scenario 8a from Ref. [62], and for the SM. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 10: Observed and expected 95% CL upper limits on the HH production cross section for seven benchmark scenarios from Ref. [61]. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 10-a: Observed and expected 95% CL upper limits on the HH production cross section for seven benchmark scenarios from Ref. [61]. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 10-b: Observed and expected 95% CL upper limits on the HH production cross section for seven benchmark scenarios from Ref. [61]. The plot on the left shows the result obtained by combining all seven search categories, while the plot on the right shows the limits obtained for each search category separately.
png pdf	Figure 11: Observed and expected limits on the HH production cross section as function of the effective coupling ${\text {c}_{2}}$ (left) and region excluded in the ${\kappa _{{\mathrm{t}}}}$ - ${\text {c}_{2}}$ plane (right). All limits are computed at 95% CL. Higgs boson couplings other than the ones shown in the plots ( ${\text {c}_{2}}$ in the left plot and ${\text {c}_{2}}$ and ${\kappa _{{\mathrm{t}}}}$ in the right plot) are assumed to have the values predicted by the SM.
png pdf	Figure 11-a: Observed and expected limits on the HH production cross section as function of the effective coupling ${\text {c}_{2}}$ (left) and region excluded in the ${\kappa _{{\mathrm{t}}}}$ - ${\text {c}_{2}}$ plane (right). All limits are computed at 95% CL. Higgs boson couplings other than the ones shown in the plots ( ${\text {c}_{2}}$ in the left plot and ${\text {c}_{2}}$ and ${\kappa _{{\mathrm{t}}}}$ in the right plot) are assumed to have the values predicted by the SM.
png pdf	Figure 11-b: Observed and expected limits on the HH production cross section as function of the effective coupling ${\text {c}_{2}}$ (left) and region excluded in the ${\kappa _{{\mathrm{t}}}}$ - ${\text {c}_{2}}$ plane (right). All limits are computed at 95% CL. Higgs boson couplings other than the ones shown in the plots ( ${\text {c}_{2}}$ in the left plot and ${\text {c}_{2}}$ and ${\kappa _{{\mathrm{t}}}}$ in the right plot) are assumed to have the values predicted by the SM.
png pdf	Figure 12: Observed and expected 95% CL upper limits on the production of new particles X of spin $0$ (top) and spin $2$ (bottom) and mass $m_{{\textrm {X}}}$ in the range 250 $\leq m_{{\textrm {X}}} \leq$ 1000 GeV, which decay to Higgs boson pairs, for the combination of all seven search categories (left) and for each search category separately (right).
png pdf	Figure 12-a: Observed and expected 95% CL upper limits on the production of new particles X of spin $0$ (top) and spin $2$ (bottom) and mass $m_{{\textrm {X}}}$ in the range 250 $\leq m_{{\textrm {X}}} \leq$ 1000 GeV, which decay to Higgs boson pairs, for the combination of all seven search categories (left) and for each search category separately (right).
png pdf	Figure 12-b: Observed and expected 95% CL upper limits on the production of new particles X of spin $0$ (top) and spin $2$ (bottom) and mass $m_{{\textrm {X}}}$ in the range 250 $\leq m_{{\textrm {X}}} \leq$ 1000 GeV, which decay to Higgs boson pairs, for the combination of all seven search categories (left) and for each search category separately (right).
png pdf	Figure 12-c: Observed and expected 95% CL upper limits on the production of new particles X of spin $0$ (top) and spin $2$ (bottom) and mass $m_{{\textrm {X}}}$ in the range 250 $\leq m_{{\textrm {X}}} \leq$ 1000 GeV, which decay to Higgs boson pairs, for the combination of all seven search categories (left) and for each search category separately (right).
png pdf	Figure 12-d: Observed and expected 95% CL upper limits on the production of new particles X of spin $0$ (top) and spin $2$ (bottom) and mass $m_{{\textrm {X}}}$ in the range 250 $\leq m_{{\textrm {X}}} \leq$ 1000 GeV, which decay to Higgs boson pairs, for the combination of all seven search categories (left) and for each search category separately (right).
png pdf	Figure 13: Distribution in BDT classifier output for resonances of spin 2 and mass 750 GeV in the 2 ${\ell}$ ss (left) and 3 ${\ell}$ (right) categories. The resonant HH signal is shown for a cross section amounting to 1 pb. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value for the HH production cross section amounts to $\hat{\sigma} =$ 0.15 $^{+0.09}_{-0.07}$ pb.
png pdf	Figure 13-a: Distribution in BDT classifier output for resonances of spin 2 and mass 750 GeV in the 2 ${\ell}$ ss (left) and 3 ${\ell}$ (right) categories. The resonant HH signal is shown for a cross section amounting to 1 pb. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value for the HH production cross section amounts to $\hat{\sigma} =$ 0.15 $^{+0.09}_{-0.07}$ pb.
png pdf	Figure 13-b: Distribution in BDT classifier output for resonances of spin 2 and mass 750 GeV in the 2 ${\ell}$ ss (left) and 3 ${\ell}$ (right) categories. The resonant HH signal is shown for a cross section amounting to 1 pb. The distributions expected for the background processes are shown for the values of the signal strength parameter $\mu$ and of the nuisance parameters obtained from the ML fit. The best-fit value for the HH production cross section amounts to $\hat{\sigma} =$ 0.15 $^{+0.09}_{-0.07}$ pb.

Tables
png pdf	Table 1: Selection requirements on ${p_{\mathrm {T}}}$ and $\eta$ of reconstructed electrons (e), muons ( $\mu$ ), and hadronically decaying tau leptons ( ${\tau _{\text {h}}}$ ) applied by the triggers used in this analysis. The trigger ${p_{\mathrm {T}}}$ thresholds for leading, subleading, and third e, $\mu$ , or ${\tau _{\text {h}}}$ are separated by commas, while a backslash indicates a threshold that depends on the year of data taking. For trigger thresholds that vary within the same year, the range of variation is indicated using an en dash.
png pdf	Table 2: Parameter values for ${\kappa _{\lambda}}$ , ${\kappa _{{\mathrm{t}}}}$ , ${\text {c}_{2}}$ , ${\text {c}_{{\mathrm{g}}}}$ , and ${\text {c}_{2 {\mathrm{g}}}}$ in MC samples modeling $20$ benchmark scenarios in the EFT approach, plus SM and "box-only'' ( $\lambda =$ 0) HH production.
png pdf	Table 3: Number of events selected in each of the seven search categories, plus two control regions (CR) for the irreducible WZ and ZZ backgrounds, described in Section 7. The HH signal represents the sum of the ggHH and qqHH production processes and is normalized to 30 times the event yield expected in the SM, corresponding to a cross section of about 1 pb. The nomenclature HHVVVV refers to the sum of HH $\rightarrow$ WWWW, WWZZ and ZZZZ decays and HHVV $\tau \tau$ refers to HH $\rightarrow$ WW $\tau \tau$ and ZZ $\tau \tau$ decays. The expected event yields are computed for the values of nuisance parameters obtained from the ML fit described in Section 9. Quoted uncertainties represent the sum of statistical and systematic components.
png pdf	Table 4: Observed (expected) 95% CL upper limits on the ggHH production cross section for the twelve benchmark scenarios from Ref. [24], the additional benchmark scenario 8a from Ref. [62] and the seven benchmark scenarios from Ref. [61]. The limits correspond to the combination of all seven search categories.

Summary

The results of a search for nonresonant as well as resonant Higgs boson pair (HH) production in final states with multiple reconstructed leptons including electrons and muons (

${\ell}$ ) as well as hadronically decaying tau leptons (

${\tau_\mathrm{h}}$ ) has been presented. The search targets the HH decay modes WWWW, WW

$\tau \tau$ , and

$\tau\tau\tau\tau$ , using proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb

$^{-1}$ , Seven search categories, distinguished by

${\ell}$ and

${\tau_\mathrm{h}}$ multiplicity, are included in the analysis: 2

${{\ell}}$ ss, 3

${{\ell} }$ , 4

${{\ell} }$ , 3

${\ell}$ + 1

${\tau_\mathrm{h}}$ , 2

${\ell}$ + 2

${\tau_\mathrm{h}}$ , 1

${\ell}$ + 3

${\tau_\mathrm{h}}$ , and 4

${\tau_\mathrm{h}}$ , where "ss" indicates two

${\ell}$ with the same charge. No evidence for a signal is found in the data and upper limits on the cross section for nonresonant as well as resonant HH production are set. The observed (expected) limits on nonresonant HH production in 20 effective field theory benchmark scenarios range from 0.21 to 1.1 (0.16 to 1.17) pb at 95% confidence level, depending on the scenario. For nonresonant HH production with event kinematics as predicted by the standard model (SM), the observed (expected) upper limit on the HH production rate is 21.8 (19.6) times the rate expected in the SM. The results of the search for nonresonant HH production are used to exclude regions in the plane of the Higgs boson coupling to the top quark,

${\text{y}_{{\mathrm{t}} }}$ , and of the trilinear Higgs boson self-coupling,

$\lambda$ . Assuming

${\text{y}_{{\mathrm{t}} }}$ has the value expected in the SM,

$\lambda$ is constrained to be between

$-$ 7.0 and 11.2 times the value expected in the SM. For resonant HH production, the observed (expected) limits on the production cross section range from 0.18 to 0.90 (0.08 to 1.07) pb, depending on the mass and spin of the resonance.

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44	ATLAS Collaboration	Search for Higgs boson pair production in the $\mathrm{b\bar{b}}\mathrm{b\bar{b}}$ final state from pp collisions at $\sqrt{s} =$ 8 TeV with the ATLAS detector	EPJC 75 (2015) 412	1506.00285
45	ATLAS Collaboration	Search for pair production of Higgs bosons in the $\mathrm{b\bar{b}}\mathrm{b\bar{b}}$ final state using proton-proton collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector	JHEP 01 (2019) 030	1804.06174
46	CMS Collaboration	Search for resonant pair production of Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at 13 TeV	JHEP 08 (2018) 152	CMS-HIG-17-009 1806.03548
47	CMS Collaboration	Search for non-resonant Higgs boson pair production in the $\mathrm{b\bar{b}}\mathrm{b\bar{b}}$ final state at $\sqrt{s} =$ 13 TeV	JHEP 04 (2019) 112	CMS-HIG-17-017 1810.11854
48	ATLAS Collaboration	Searches for Higgs boson pair production in the $\mathrm{H}\mathrm{H} \to \mathrm{b\bar{b}}\tau\tau,$ \gamma\gamma\mathrm{W}\mathrm{W}^{*} $,$ \gamma\gamma\mathrm{b\bar{b}} $,$ \mathrm{b\bar{b}}\mathrm{b\bar{b}} $ channels with the ATLAS detector	PRD 92 (2015) 092004	1509.04670
49	CMS Collaboration	Search for Higgs boson pair production in the $\mathrm{b\bar{b}}\tau\tau$ final state in proton-proton collisions at $\sqrt{s} =$ 8 TeV	PRD 96 (2017) 072004	CMS-HIG-15-013 1707.00350
50	CMS Collaboration	Search for Higgs boson pair production in events with two bottom quarks and two tau leptons in pp collisions at $\sqrt{s} =$ 13 TeV	PLB 778 (2018) 101	CMS-HIG-17-002 1707.02909
51	ATLAS Collaboration	Search for resonant and non-resonant Higgs boson pair production in the $\mathrm{b\bar{b}}\tau^{+}\tau^{-}$ decay channel in pp collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector	PRL 121 (2018) 191801	1808.00336
52	CMS Collaboration	Search for resonant and non-resonant Higgs boson pair production in the $\mathrm{b\bar{b}}\ell\nu\ell\nu$ final state in proton-proton collisions at $\sqrt{s} =$ 13 TeV	JHEP 01 (2018) 054	CMS-HIG-17-006 1708.04188
53	ATLAS Collaboration	Search for Higgs boson pair production in the $\gamma\gamma\mathrm{W}\mathrm{W}^{*}$ channel using pp collision data recorded at $\sqrt{s} =$ 13 TeV with the ATLAS detector	EPJC 78 (2018) 1007	1807.08567
54	CMS Collaboration	Combination of searches for Higgs boson pair production in proton-proton collisions at $\sqrt{s} =$ 13 TeV	PRL 122 (2019) 121803	CMS-HIG-17-030 1811.09689
55	CMS Collaboration	Performance of the CMS Level-1 trigger in proton-proton collisions at $\sqrt{s} =$ 13 TeV	JINST 15 (2020) P10017	CMS-TRG-17-001 2006.10165
56	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
57	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
58	CMS Collaboration	Precision luminosity measurement in proton-proton collisions at $\sqrt{s} =$ 13 TeV in 2015 and 2016 at CMS	EPJC 81 (2021) 800	CMS-LUM-17-003 2104.01927
59	CMS Collaboration	CMS luminosity measurement for the 2017 data-taking period at $\sqrt{s} =$ 13 TeV	CMS-PAS-LUM-17-004	CMS-PAS-LUM-17-004
60	CMS Collaboration	CMS luminosity measurement for the 2018 data-taking period at $\sqrt{s} =$ 13 TeV	CMS-PAS-LUM-18-002	CMS-PAS-LUM-18-002
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72	S. Alioli, S.-O. Moch, and P. Uwer	Hadronic top-quark pair-production with one jet and parton showering	JHEP 01 (2012) 137	1110.5251
73	S. Alioli, P. Nason, C. Oleari, and E. Re	NLO single-top production matched with shower in POWHEG: s- and t-channel contributions	JHEP 09 (2009) 111	0907.4076
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76	S. Alioli, P. Nason, C. Oleari, and E. Re	NLO Higgs boson production via gluon fusion matched with shower in POWHEG	JHEP 04 (2009) 002	0812.0578
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83	B. Hespel, D. Lopez-Val, and E. Vryonidou	Higgs pair production via gluon fusion in the two-Higgs-doublet model	JHEP 09 (2014) 124	1407.0281
84	A. Oliveira	Gravity particles from warped extra dimensions, predictions for LHC		1404.0102
85	NNPDF Collaboration	Parton distributions for the LHC Run II	JHEP 04 (2015) 040	1410.8849
86	NNPDF Collaboration	Parton distributions from high-precision collider data	EPJC 77 (2017) 663	1706.00428
87	J. Butterworth et al.	PDF4LHC recommendations for LHC Run II	JPG 43 (2016) 023001	1510.03865
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95	CMS Collaboration	Particle-flow reconstruction and global event description with the CMS detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
96	M. Cacciari, G. P. Salam, and G. Soyez	The anti- ${k_{\mathrm{T}}}$ jet clustering algorithm	JHEP 04 (2008) 063	0802.1189
97	M. Cacciari, G. P. Salam, and G. Soyez	$FastJet$ user manual	EPJC 72 (2012) 1896	1111.6097
98	CMS Collaboration	Performance of electron reconstruction and selection with the CMS detector in pp collisions at $\sqrt{s} =$ 8 TeV	JINST 10 (2015) P06005	CMS-EGM-13-001 1502.02701
99	CMS Collaboration	Measurement of the Higgs boson production rate in association with top quarks in final states with electrons, muons, and hadronically decaying tau leptons at $\sqrt{s} =$ 13 TeV	EPJC 81 (2021) 378	CMS-HIG-19-008 2011.03652
100	CMS Collaboration	Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $\sqrt{s} =$ 13 TeV	JINST 13 (2018) P06015	CMS-MUO-16-001 1804.04528
101	CMS Collaboration	Performance of reconstruction and identification of $\tau$ leptons decaying to hadrons and $\nu_{\tau}$ in pp collisions at $\sqrt{s} =$ 13 TeV	JINST 13 (2018) P10005	CMS-TAU-16-003 1809.02816
102	CMS Collaboration	Performance of the DeepTau algorithm for the discrimination of taus against jets, electrons, and muons	CMS-DP-2019-033
103	Y. Lecun	Generalization and network design strategies	of the University of Toronto, CRG-TR-89-4
104	CMS Collaboration	Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV	JINST 12 (2017) P02014	CMS-JME-13-004 1607.03663
105	CMS Collaboration	Search for resonances decaying to a pair of Higgs bosons in the $\mathrm{b\bar{b}}\mathrmP\{q\bar{q}}'\ell\nu$ final state in proton-proton collisions at $\sqrt{s} =$ 13 TeV	JHEP 10 (2019) 125	1904.04193
106	CMS Collaboration	CMS Phase 1 heavy flavour identification performance and developments	CMS-DP-2017-013
107	CMS Collaboration	Performance of missing transverse momentum reconstruction in proton-proton collisions at $\sqrt{s} =$ 13 TeV using the CMS detector	JINST 14 (2019) P07004	CMS-JME-17-001 1903.06078
108	CMS Collaboration	Evidence for associated production of a Higgs boson with a top quark pair in final states with electrons, muons, and hadronically decaying $\tau$ leptons at $\sqrt{s} =$ 13 TeV	JHEP 08 (2018) 066	CMS-HIG-17-018 1803.05485
109	CMS Collaboration	Search for non-resonant Higgs boson pair production in the four leptons plus two b jets final state in proton-proton collisions at $\sqrt{s} =$ 13 TeV	CMS-PAS-HIG-20-004	CMS-PAS-HIG-20-004
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122	CMS Collaboration	Search for nonresonant Higgs boson pair production in final states with two bottom quarks and two photons in proton-proton collisions at $\sqrt{s} =$ 13 TeV	JHEP 03 (2021) 257	CMS-HIG-19-018 2011.12373
123	ATLAS Collaboration	Combination of searches for Higgs boson pairs in pp collisions at s=13TeV with the ATLAS detector	PLB 800 (2020) 135103	1906.02025
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