Constraining the Higgs boson self-coupling from single- and double-Higgs production with the ATLAS detector using $pp$ collisions at $\sqrt{s}=13$ TeV

The collaboration
CERN-EP-2022-149, 2022.

Abstract (data abstract)
Constraints on the Higgs boson self-coupling are set by combining double-Higgs boson analyses in the bbbb, bb$\tau\tau$ and bb$\gamma\gamma$ decay channels with single-Higgs boson analyses targeting the $\gamma\gamma$, $ZZ^{∗}$, $WW^{∗}$, $\tau\tau$ and bb decay channels. The data used in these analyses were recorded by the ATLAS detector at the LHC in proton−proton collisions at 13 TeV and correspond to an integrated luminosity of 126−139 fb$^{-1}$ . The combination of the double-Higgs analyses sets an upper limit of $\mu_{HH} < 2.4$ at 95% confidence level on the double-Higgs production cross-section normalised to its Standard Model prediction. Combining the single-Higgs and double-Higgs analyses, with the assumption that new physics affects only the Higgs boson self-coupling ($\lambda_{HHH}$), values outside the interval $-0.4< \kappa_\lambda < 6.3$ are excluded at 95% confidence level. The combined single-Higgs and double-Higgs analyses provide results with fewer assumptions, by adding in the fit more coupling modifiers introduced to account for the Higgs boson interactions with the other Standard Model particles.