SMuK 2023 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 5: Searches (Higgs, ALPS and more)

T 5.1: Vortrag

Montag, 20. März 2023, 16:30–16:45, HSZ/0101

An interference search for heavy Higgs bosons decaying to a top-antitop-quark pair with the ATLAS detector — •Nicola de Biase, Katharina Behr, and Eleanor Jones — Deutsches Elektronen-Synchrotron

New pseudoscalar (A) and scalar (H) states coupling strongly with tt states are predicted by many models with an extended Higgs sector, such as two-Higgs Doublet Models (2HDMs), which add a second Higgs doublet to the SM. In 2HDMs with fermion coupling structure of type II, these states decay predominantly to tt, provided that they are massive enough (m>500 GeV) and that the ratio between the vacuum-expectation-values of the two Higgs doublets (tanβ) is small (tanβ 3). To date, this parameter region is only little constrained by direct searches, as any search in the tt final state is complicated by the interference between the signal process (gluon-gluon initiated A/H production) and the dominant and irreducible background, which is the Standard Model production of tt pairs. This interference produces a characteristic peak-dip structure in the tt mass spectrum. In this talk, a search for pseudoscalar and scalar states decaying to a pair of top-quarks will be presented, using the full Run-II ATLAS dataset. Special attention will be given to the conceptual and technical challenges regarding the treatment of interference effects in the statistical analysis of the data.