Angular Analysis of the $B^{0} \rightarrow K^{*0}\mu^{+}\mu^{-}$ decay at the LHCb experiment

An angular analysis of the $B^{0}\rightarrow K^{*0}(\to K^{+}\pi^{-})\mu^{+}\mu^{-}$ decay is presented in this thesis. The measurement uses a data set corresponding to an integrated luminosity of $4.7{\mbox{fb}^{-1}}$ of $pp$ collision data collected with the LHCb detector during the years $2011$, $2012$ and $2016$. Angular observables are determined in bins of the invariant dimuon mass squared using an unbinned maximum likelihood fit, in which contamination from decays with the $K^{+}\pi^{-}$ system in an S-wave configuration is taken into account. The results of the observables are the most precise to date, reducing the uncertainty with respect to the previous LHCb measurements by approximately $30\%$. The tension that was previously observed with the Standard Model predictions persists, and studies with the flavio software package indicate a slight increase in the tension. However, the precise value depends on the choice of theory nuisance parameters.