Universal Extra Dimensions
Abstract: In this talk, I will describe a 5D world in the framework of the model of universal extra dimensions. As an application, I will focus on the contributions to certain rare processes of the top quark. It is calculated that the top quark decays into a charm quark, accompanied by a neutral gauge boson or a Higgs particle, with a probability of 10-14 to 10-11 within the scope of the Standard Model. However, experiments yield only an upper bound for these processes, which is nearly of order 10-3. If such high probabilities are observed, this would signal new physics. It is in an extra-dimensional world scenario that we hope to account for these tremendous orders of gap. The results obtained in the minimal extension of the Standard Model to universal extra dimensions will be presented at the end.