Study of $t\bar{t}H$ and $tH$ production in the $H\to \tau \tau$ channel in $pp$ collisions at $\sqrt{s}=13$ TeV and 13.6 TeV with the ATLAS detector

Abstract

A study of the production of the Higgs boson in association with either a top-quark pair ($t\bar{t}H$) or a single top quark ($tH$) in the $\tau$-lepton-pair decay channel is presented. The analysis relies on final states featuring fully hadronic decays of the top quarks and the $\tau$-leptons. It employs data samples of proton--proton collisions at $\sqrt{s}=13$ and 13.6 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider and corresponding to integrated luminosities of 140 fb${}^{-1}$ and 161 fb${}^{-1}$, respectively. The measured signal strength ($\mu$), defined as the measured cross-section normalised to the Standard Model prediction, is ${\mu }_{t\bar{t}H}=1.51_{-0.62}^{+0.71}$ for $t\bar{t}H$ and ${\mu }_{tH}=-0.4_{-5.1}^{+5.6}$ for $tH$. Additionally, the $t\bar{t}H$ cross-section is measured differentially in three bins of the Higgs boson transverse momentum in the simplified template cross-section framework.

37 pages in total, author list starting page 21, 5 figures, 2 tables, submitted to JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGP-2024-52/