Effective field theories in the standard model and beyond

Two applications of effective field theories are studied. In the first part we discuss exclusive hadronic decays of the electroweak bosons Z, W and the Higgs in the framework of QCD factorization. The factorization formula is derived using Soft-Collinear Effective Theory and then applied to the decays Z→Mγ, W→Mγ, Z→MW, h→Mγ, h→MZ and h→MW, where M is a meson. We derive predictions for the radiative decays at next-to-leading order in QCD and resum large logarithms of the form α_s log(μ₀/v), where v denotes the electroweak scale and μ₀ is the hadronic scale. We show that power corrections in the expansion parameter are negligible because they are effectively suppressed with at least m_M/v, where m_M is the mass of the final-state meson M. The analysis of the Higgs decays is performed allowing for deviations from the SM couplings of the Higgs to predict the sensitivity of the branching ratios to new-physics effects. Due to a non-trivial interference structure of different decay amplitudes we find a strong sensitivity to new physics in some decay channels. In the second part we study renormalization group effects on neutrino oscillation parameters in type-I seesaw models. Assuming a flavor-anarchic scenario chosen at a high-scale, we estimate the probability of the observed oscillation parameters to be the results of a random drawing. We show how this probability changes when renormalization group effects are carefully taken into account.