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T: Fachverband Teilchenphysik

T 70: Experimental Methods (general) 3

T 70.5: Vortrag

Mittwoch, 23. März 2022, 17:15–17:30, T-H29

Utilizing muons to tag b-jets in ATLAS — •Frederic Renner, Clara Elisabeth Leitgeb, and Cigdem Issever — DESY, Zeuthen, Germany

Several Beyond Standard Model theories predict Higgs boson pair production with much larger cross sections compared to the Standard Model. While Higgs boson pair production has not yet been observed at the LHC due to the rarity of the process, it may come within reach with more data in upcoming runs with improved statistics and improved particle reconstruction. A Higgs boson pair decays predominantly into four b-quarks, which makes the identification of jets originating from b-quarks particularly important. B-quarks have a longer lifetime than lighter quarks, leading to a second displaced vertex separated from the primary vertex which is mainly exploited in b-tagging algorithms. However, when using the results in a neural network to distinguish the flavor origin of jets, the network still misidentifies a lot of jets originating from lighter quarks as b-quark jets. About 20% of b-quarks decay semileptonically with a so-called soft muon in the final state. They are soft because they are generally less energetic than particles originating from the primary vertex. Utilizing the muon information, the rejection of fake b-jets can be improved substantially at a given selection efficiency.