A search for Higgs boson pair production in events with two b-jets and two tau -leptons is presented, using a proton-proton collision dataset with an integrated luminosity of 139 fb(-1) collected at root s = 13TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one tau-lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3.1 sigma (2.0 sigma). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance.

Aad, G., Abbott, B., Abbott, D.C., Abed Abud, A., Abeling, K., Abhayasinghe, D.K., et al. (2023). Search for resonant and non-resonant Higgs boson pair production in the $$ b\overline{b}{\tau}^{+}{\tau}^{-} $$ decay channel using 13 TeV pp collision data from the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 2023(7) [10.1007/jhep07(2023)040].

Search for resonant and non-resonant Higgs boson pair production in the $$ b\overline{b}{\tau}^{+}{\tau}^{-} $$ decay channel using 13 TeV pp collision data from the ATLAS detector

I. Bashta;M. T. Camerlingo;V. D'Amico;B. Di Micco;R. Di Nardo;D. Orestano;F. Petrucci;