Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B.; Abhayasinghe, D. K.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adelman, J.; Adersberger, Michael; Adiguzel, A.; Adye, T.; Affolder, A. A.; Afik, Y.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akesson, T. P. A.; Akilli, E.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albicocco, P. (2018): Search for Resonant and Nonresonant Higgs Boson Pair Production in the bb[over ¯]τ^{+}τ^{-} Decay Channel in pp Collisions at sqrt[s]=13  TeV with the ATLAS Detector. In: Physical Review Letters, Vol. 121, No. 19
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### Abstract

A search for resonant and nonresonant pair production of Higgs bosons in the bbover tau{\^{}}{+}tau{\^{}}{-} final state is presented. The search uses 36.1 fb{\^{}}{-1} of pp collision data with sqrts=13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. Decays of the tau-lepton pairs with at least one tau 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 X in the mass range 305 GeV{\textless}m{\_}{X}{\textless}402 GeV in the simplified hMSSM minimal supersymmetric model for tanbeta=2 and excluding bulk Randall-Sundrum gravitons G{\_}{KK} in the mass range 325 GeV{\textless}m{\_}{G_{KK}}{\textless}885 GeV for k/Mover {\_}{Pl}=1.