Abstract

A search for non-resonant Higgs boson pair ($HH$) production is presented, in which one of the Higgs bosons decays to a b-quark pair ($b\bar b$) and the other decays to $WW^*$, $ZZ^*$, or $\tau^+\tau^-$, with in each case a final state with $\ell^+\ell^- +$ neutrinos ($\ell = e, \mu$). The analysis targets separately the gluon-gluon fusion and vector boson fusion production modes. Data recorded by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of $140\mathrm{fb}^{-1}$, are used in this analysis. Events are selected to have exactly two $b$-tagged jets and two leptons with opposite electric charge and missing transverse momentum in the final state. These events are classified using multivariate analysis algorithms to separate the $HH$ events from other Standard Model processes. No evidence of the signal is found. The observed (expected) upper limit on the cross-section for non-resonant Higgs boson pair production is determined to be 9.7 (16.2) times the Standard Model prediction at 95% confidence level. The Higgs boson self-interaction coupling parameter $\kappa_\lambda$ and the quadrilinear coupling parameter $\kappa_{2V}$ are each separately constrained by this analysis to be within the ranges ${[-6.2, 13.3]}$ and ${[-0.17, 2.4]}$, respectively, at 95% confidence level, when all other parameters are fixed.

Table 1 (pre-fit yields)

Data from figure 4 of the paper

10.17182/hepdata.144917.v1/t1

Pre-fit yields of the $t\bar{t}$, $Z$+HF and $Wt$ CRs, both for the ggF and VBF event selection, as well as...
Table 2 (post-fit yields)

Data from figure 5 of the paper

10.17182/hepdata.144917.v1/t2

Post-fit yields from the signal+background fit of the $t\bar{t}$, $Z$+HF and $Wt$ CRs, both for the ggF and VBF event...
Table 3 (95% CL upper limits on cross-section)

Data from figure 6 of the paper

10.17182/hepdata.144917.v1/t3

Observed and expected upper limits on the ratios of the Higgs boson pair production cross-section to the corresponding Standard Model...
Table 4 ($\kappa_\lambda$ likelihood profile)

Data from figure 7(a) of the paper

10.17182/hepdata.144917.v1/t4

Likelihood profiles of the $\kappa_\lambda$ parameter.
Table 5 ($\kappa_{2V}$ likelihood profile)

Data from figure 7(b) of the paper

10.17182/hepdata.144917.v1/t5

Likelihood profiles of the $\kappa_{2V}$ parameter.
Table 6 ($\kappa_\lambda$ scan)

Data from figure 5 in the auxiliary material

10.17182/hepdata.144917.v1/t6

The 95% CL upper limits on the $HH$ cross-section for different values of $\kappa_\lambda$. The expected limits assume no $HH$...
Table 7 ($\kappa_{2V}$ scan)

Data from figure 6 in the auxiliary material

10.17182/hepdata.144917.v1/t7

The 95% CL upper limits on the VBF $HH$ cross section for different values of $\kappa_{2V}$. The expected limits assume...

Table 1 (pre-fit yields)

Table 2 (post-fit yields)

Table 3 (95% CL upper limits on cross-section)

Table 4 ($\kappa_\lambda$ likelihood profile)

Table 5 ($\kappa_{2V}$ likelihood profile)

Table 6 ($\kappa_\lambda$ scan)

Table 7 ($\kappa_{2V}$ scan)

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