Thesis BELLE2-MTHESIS-2022-005

Study of charmless B → η′K decays with the Belle II experiment

Valeria Fioroni ; Stefano Lacaprara

Dipartimento di Fisica e Astronomia “Galileo Galilei” Padova

Abstract: The study of penguin-dominated B0 → η′K0S decays provides a good test of the Standard Model, since the CP violation measurement in this mode is sensitive to the presence of new physics effects in the loop. In this work, a precise description of the signal extraction for both charged and neutral B → η′K decays is presented, focusing on the suppression of the main background component: the continuum. A FastBDT classifier is trained to separate continuum and signal candidates, using variables related to the event topology. Furthermore, a study on multivariate Monte Carlo reweighting has been performed, in order to reduce the impact of the Monte Carlo mismodelling of the continuum suppression variables on the systematic uncertainty. From the measured signal yield, a branching fraction measurement has been performed, obtaining results consistent with world averages. Finally, a study on the signal ∆t resolution function is presented.

Note: Presented on 13 12 2021
Note: MSc

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 Record created 2022-03-24, last modified 2022-03-24

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