Constraining the Higgs boson self-coupling via single-Higgs production measurement

Constraints on the Higgs boson self-coupling, $\lambda_{HHH}$, exploiting measurements of the single-Higgs boson production and decays are reported in this note. The Higgs boson cross sections, the branching fractions and the Higgs boson kinematics are affected by the Higgs-boson self coupling contribution through Next-to-Leading Order electroweak corrections. The results are obtained using up to 80 fb$^{-1}$ of LHC pp collision at $\sqrt{s}=13$ TeV collected with the ATLAS experiment, combining the data of the analyses targeting the $\gamma\gamma$, $ZZ^*$, $WW^*$, $\tau\tau$, $b\bar{b}$ decay channels and using both inclusive and differential information. In the simplified assumption that all deviations from the SM expectation have to be interpreted as modifications of the trilinear coupling of the Higgs boson, the best fit value of $\kappa_\lambda$, defined as the ratio $\kappa_\lambda=\lambda_{HHH}/ \lambda_{HHH}^{SM}$, is $\kappa_\lambda=4.0^{+4.3}_{-4.1}$ excluding at the 95\% C.L. values outside the interval $-3.2 < \kappa_\lambda < 11.9