%0 Generic
%A Gerick, David
%C Heidelberg
%D 2021
%F heidok:29883
%K Physik, Elementarteilchenphysik, LHC, LHCb, Standardmodell, Datenanalyse, Flavor Anomalien
%R 10.11588/heidok.00029883
%T Search for physics beyond the standard model in an angular analysis of the B⁺→K*⁺μ⁺μ⁻ decay at LHCb
%U https://archiv.ub.uni-heidelberg.de/volltextserver/29883/
%X In this thesis an angular analysis of the B⁺→K*⁺μ⁺μ⁻ decay with the subsequent decays K*⁺→K⁰Sπ⁺ and K⁰S→π⁺π⁻ is presented. The full data set collected by the LHCb experiment during the first two periods of pp collisions at the Large Hadron Collider in the years 2011-2018 is used. In total, 737±34 signal candidates are selected, which allows to determine all angular observables and their correlations in the B⁺→K*⁺μ⁺μ⁻ decay for the first time. Furthermore, it is the first time that all angular observables are measured in a b→sl⁺l⁻ transition other than that included in the decay of the neutral B⁰ meson. A four-dimensional maximum-likelihood fit is used to extract two sets of angular observables in ten intervals of the invariant dimuon mass squared, q². For most observables and in most q² intervals the resulting values are compatible with Standard Model predictions. However, most prominently the CP-averaged (and optimised) angular observables Afb (P2) and S5 (P5') show significant discrepancies from Standard Model predictions in the q² region below the J/ψ resonance. A global evaluation of the result in terms of the real part of the underlying vector coupling strength in the model-independent effective field theory description prefers a shift of ∆Re(C9)=−1.9 from the Standard Model value with a significance of 3.1σ.  The pattern of deviation is coherent with previous measurements in the isospin-partner decay of the B⁰ meson. The size of the deviation largely depends on the considered q² regions and choice of theory nuisance parameters for the global fit.