Thesis BELLE2-MTHESIS-2021-064

Search for B -> K(*)νν decays in the Belle II experiment

Güney Polat ; Isabelle Ripp-Baudot

IPHC Strasbourg

Abstract: The B -> K(*)νν decay channel, never discovered to this day, is actively sought in the Belle II experiment: its branching ratio is in the order of magnitude of 10^(−6) and could be significantly changed if new physics occurred in the decay process. During this internship, we analysed simulations of events produced inside the experiment’s collider SuperKEKB by electron-positron collisions. This analysis consists of the reconstruction of B mesons decays from simulations, in order to apply afterwards a selection optimised with the Punzi figure of merit and to retain only the events corresponding to the B0 → K(*0)νν channel, while rejecting the rest. Finally, we expect 0.9 ± 0.04 signal event and 1 ± 1 background event, for a luminosity of 1 ab^(−1). The efficiency of the signal selection procedure is (5.31 ± 0.27)%, without taking into account a first selection from the decay's reconstruction. An estimation of an upper limit on the branching ration still has to be done, with the help of statistical methods we need to study.

Note: Presented on 21 06 2019
Note: MSc

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 Record created 2021-07-01, last modified 2021-07-01

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