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T: Fachverband Teilchenphysik

T 95: Searches for Dark Matter III

T 95.5: Vortrag

Donnerstag, 18. März 2021, 17:00–17:15, Tt

Exploiting W-tagging in a tW+MET signature Dark Matter search with the ATLAS experiment — •Ben Brüers, Paul Moder, Priscilla Pani, Claudia Seitz, and Alvaro Lopez Solis — DESY, Hamburg and Zeuthen, Germany

Dark Matter (DM) remains one of the unrevealed mysteries of the universe. Even though it constitutes ∼ 80 % of the matter, considerably little is known about DM, despite it significantly influences the dynamics of galaxies and the expansion of the universe. The search for DM at colliders, probing mainly a particle nature of the unknown matter, marks an important pillar in exploring all possible realisations of DM. From the variety of DM models, this talk will present a search for DM with the ATLAS experiment, where the DM is coupled to the Standard Model (SM) via a pseudo-scalar mediator that is added to a two-Higgs-doublet model (2HDM+a). Being enhanced by a diagram in which a charged Higgs-boson H⁺ decays into the mediator and a W-boson, the associated production of DM with a W-boson and a top-quark is considered. The DM leaves a signature of missing transverse energy (MET) in the detector. For heavy H⁺, the W-boson is boosted, meaning that if decaying hadronically, the two jets from its decay are merged into one large-radius jet. Since after preselection only few boosted W bosons are expected from the backgrounds, tagging boosted W’s appears efficient to distinguish signal and backgrounds. The talk will introduce W-tagging techniques and their performance. Furthermore some first results of the application of W-tagging in the tW+MET analysis will be shown.