Thesis / Dissertation

# Measurement of the branching fractions of $\bar{B}^{0}\to D^{* } h^{-}$ decays at the Belle experiment and development of a global particle vertex fitting algorithm for Belle~II

Jo-Frederik Krohn, Phillip Urquijo (ed.)

Published : 2021

#### Abstract

In this thesis high precision QCD-factorisation tests were performed. The branching ratios B(B → D π ) = (2.67±0.02±0.09)×10 and B(B → D K ) = (2.27±0.06±0.08)×10−4 were measured using (771.58±10.56)×106 B-meson pairs recorded by the Belle experiment. Both values are in tension with the theoretical expectation. The ratio of the branching ratio is measured in a way that allows for the cancellation of the systematic uncertainties arising from the D∗-meson reconstruction; the value of RK/π = B(B → D K )/B(B → D π ) = (8.41±0.24±0.13)×10 was found. Both B(B → D π ) and B(B → D K ) have shown deviations from the prediction, this suggests that the estimation of the Feynman diagrams contributin..

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