Top Physics in Atlas

Naranjo, Roger

doi:10.1142/9789813224568_0035

Cited by 1 publication

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“…The top quark was discovered at Tevatron in 1995 [1,2], and since then it has become an object of exhaustive analysis [3]. With the start of the LHC, which can be seen as a top-factory, the study of the top quark entered into a new stage [4][5][6][7][8][9] with unique challenges. In particular, because of the high energies achieved at the LHC, highly boosted top quarks with transverse momentum above p T ≳ 300 GeV are copiously produced.…”

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confidence: 99%

Exploring unsupervised top tagging using Bayesian inference

et al. 2023

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Recognizing hadronically decaying top-quark jets in a sample of jets, or even its total fraction in the sample, is an important step in many LHC searches for Standard Model and Beyond Standard Model physics as well. Although there exists outstanding top-tagger algorithms, their construction and their expected performance rely on Montecarlo simulations, which may induce potential biases. For these reasons we develop two simple unsupervised top-tagger algorithms based on performing Bayesian inference on a mixture model. In one of them we use as the observed variable a new geometrically-based observable \tilde{A}_{3}Ã3, and in the other we consider the more traditional \tau_{3}/\tau_{2}τ3/τ2NN-subjettiness ratio, which yields a better performance. As expected, we find that the unsupervised tagger performance is below existing supervised taggers, reaching expected Area Under Curve AUC \sim 0.80-0.81∼0.80−0.81 and accuracies of about 69% -− 75% in a full range of sample purity. However, these performances are more robust to possible biases in the Montecarlo that their supervised counterparts. Our findings are a step towards exploring and considering simpler and unbiased taggers.

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