ATLAS Collab.
Reconstruction and identification of boosted di-τ systems in a search for Higgs boson pairs using 13 TeV proton−proton collision data in ATLAS
In this paper, a novel technique, referred to as the di-τ tagger, is designed to reconstruct and identify hadronically decaying τ+τ− pairs with a large Lorentz boost in the ATLAS experiment at the Large Hadron Collider. A benchmark di-τ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted bb pair and the other into a boosted τ+τ− pair, with two hadronically decaying τ-leptons in the final state. Using 139 fb−1 of proton−proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di-τ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di-τ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon−gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1−3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model.