Constraints on the Higgs boson self-coupling from single- and double-Higgs production with the ATLAS detector using pp collisions at root s=13 TeV

The Higgs boson (H) trilinear self-coupling, lamba_3, is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at root s = 13 TeV. The combination of event categories enriched in single-H and HH events is used to measure kappa_lambda, defined as the value of lambda_3 normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of kappa_lambda outside the interval -1.2 < kappa_lambda < 7.5 are excluded at 2 sigma confidence level, which is compatible with the expected range of -2.0 < kappa_lambda < 7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) kappa_lambda interval is constrained to be within -1.4 < kappa_lambda < 7.8 (-2.3 < kappa_lambda < 7.8) at 2 sigma confidence level.