Abstract
An amplitude analysis of the B0 → K∗0μ+μ− decay is presented in this thesis. The measurement makes use of data samples collected by the LHCb experiment between the years 2011 and 2018, which correspond to an integrated luminosity of 9 fb−1 pp collision data. This analysis performs an unbinned fit using a model that considers the differential branching fractions of the B0 → K∗0μ+μ− decay, which can be written in the basis of the K∗0 transversity amplitudes, with acceptance effects and background taken into account. The transversity amplitudes are measured as functions of dimuon invariant mass squared, q2, and are modelled with Legendre polynomial ansatzes aiming to remove model dependencies as much as possible from the description of experimental datasets. These amplitudes contain P-wave amplitudes, while the S-wave amplitudes of the Kπ system are also accounted for.This analysis is performed in two q2 regions, 1.25 < q2 < 8.0 GeV2/c4 and 11.0 < q2 < 12.5 GeV2/c4. In both regions, the likelihood surfaces of individual parameters are carefully examined. The results in the 1.25 < q2 < 8.0 GeV2/c4 region present correct statistical coverage while the results from the 11.0 < q2 < 12.5 GeV2/c4 region still need further investigation. The best-fit points of the P-wave amplitudes with uncertainties and correlations will be provided as the final result of this analysis, such that synthetic datasets with the acceptance effects and background subtracted can be generated. Theorists can then use any model to fit the synthetic data to determine the vector current (C9) and axial-vector current (C10) Wilson coefficients. The theoretical models chosen can potentially provide an explanation for the anomalies seen in b → sℓ+ℓ− transitions.
| Date of Award | 1 Oct 2024 |
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| Original language | English |
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| Supervisor | Konstantinos A. Petridis (Supervisor) & Jonas H Rademacker (Supervisor) |