An empirical model to determine the hadronic resonance contributions to transitions.

A method for analysing the hadronic resonance contributions in decays is presented. This method uses an empirical model that relies on measurements of the branching fractions and polarisation amplitudes of final states involving resonances, relative to the short-distance component, across the full dimuon mass spectrum of transitions. The model is in good agreement with existing calculations of hadronic non-local effects. The effect of this contribution to the angular observables is presented and it is demonstrated how the narrow resonances in the spectrum provide a dramatic enhancement to -violating effects in the short-distance amplitude. Finally, a study of the hadronic resonance effects on lepton universality ratios, , in the presence of new physics is presented.