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Abstract

The standard model Higgs mass term receives quadratically divergent radiative corrections, thereby destabilizing the electroweak scale. In classically conformally invariant models, a hierarchy between the electroweak and the Planck scale is naturally introduced and stabilized since the electroweak scale itself is induced by radiative corrections. The recent observation of non-vanishing neutrino masses furthermore requires an extension of the standard model. Leftright symmetric models offer a natural framework for neutrino masses and are therefore theoretically appealing. In this thesis, the radiative breaking of the minimal conformally invariant leftright symmetric model is discussed. It is shown that the renormalization group running naturally creates a large hierarchy between the Planck scale and the the left-right breaking scale, thereby providing a natural solution to the hierarchy problem of elementary particle physics. It is pointed out that, to obtain a hierarchy between the electroweak and the left-right scale some rather mild fine-tuning in the model parameters is needed. A possible scenario is discussed that is consistent with low-energy phenomenology, and first steps are taken in the direction of a phenomenological discussion of this model.