43rd International Conference on High Energy Physics

Search for the associated production of a Higgs boson and a single top quark in the 𝑯 → 𝝉𝝉 decay mode and combined measurement of tH production using pp collisions at 13 TeV with the ATLAS detector

Not scheduled

20m

Natal, Brazil

Poster

Speaker

Reisaburo Tanaka (IJCLab, Université Paris-Saclay (FR))

Description

A search for the production of a Higgs boson in association with a single top quark in multi-lepton final states including a 𝜏 lepton is presented, using an integrated luminosity of 140/fb of proton–proton collision data at a centre-of-mass energy of √𝑠 = 13 TeV collected by the ATLAS detector at the LHC. The analysis targets the 𝐻 → 𝜏𝜏 decay, where at least one 𝜏-lepton decays hadronically, to indicate the presence of the Standard Model Higgs boson. No significant excess over the expected background is observed, and an observed (expected) upper limit at the 95% confidence level on the signal strength is set at 8.6 (9.3) times the Standard Model prediction. This measurement is combined with previous publications of the ATLAS collaboration targeting the same production process but in different final states. The combined measurement of the signal strength yields 𝜇(𝑡𝐻) = 4.5 +2.3(−2.1) = 4.5 ± 1.5 (stat.) +1.7(−1.4) (sys.) times the Standard Model expectation, corresponding to an observed tH significance of 2.3 standard deviations. The combined observed (expected) upper limit at the 95% confidence level on the signal strength is set at 8.5 (3.9) times the Standard Model prediction.