Search for heavy resonances decaying into two Higgs bosons in the ${\text {b}}\bar{\textrm{b}}\tau ^{+}\tau ^{-}$ final state in proton–proton collisions at $\sqrt{s} = 13\,\text {TeV}$

A search is presented for massive narrow-width resonances in the mass range of 1–4.5 TeV, decaying into pairs of Higgs bosons (HH). The search uses proton–proton collision data at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis targets final states where one Higgs boson decays into a pair of bottom quarks and the other into a pair of tau leptons, X -> HH -> b$\overline{b}$$\tau ^{+}\tau ^{-}$. It uses a single large radius jet to reconstruct the H -> b$\overline{b}$ decay, while the H -> $\tau ^{+}\tau ^{-}$ decay products can either be contained within a single large radius jet or appear as two isolated tau leptons. The observed data are consistent with standard model background expectations. Upper limits at 95% confidence level are set on the production cross section for resonant HHproduction for masses between 1 and 4.5 TeV. This analysis sets the most sensitive limits to date on X -> HH -> b$\overline{b}$$\tau ^{+}\tau ^{-}$ decays in the mass range of 1.4–4.5 TeV.