Abstract
A search for resonant and nonresonant pair production of Higgs bosons in the πβ’Β―πβ’π+β’πβ final state is presented. The search uses 36.1ββfbβ1 of πβ’π collision data with βπ =13ββTeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. Decays of the π-lepton pairs with at least one π lepton decaying to final states with hadrons and a neutrino are considered. No significant excess above the expected background is observed in the data. The cross-section times branching ratio for nonresonant Higgs boson pair production is constrained to be less than 30.9 fb, 12.7 times the standard model expectation, at 95% confidence level. The data are also analyzed to probe resonant Higgs boson pair production, constraining a model with an extended Higgs sector based on two doublets and a Randall-Sundrum bulk graviton model. Upper limits are placed on the resonant Higgs boson pair production cross-section times branching ratio, excluding resonances π in the mass range 305ββGeV<ππ<402ββGeV in the simplified hMSSM minimal supersymmetric model for tanβ‘π½ =2 and excluding bulk Randall-Sundrum gravitons πΊKK in the mass range 325ββGeV<ππΊKK<885ββGeV for π/Β―πPl=1.