Electroweak and flavor physics in extensions of the standard model with large extra dimensions

We study the implications of extra dimensions of size R similar to 1/TeV on electroweak and flavor physics due to the presence of Kaluza-Klein excitat ions of the SM gauge-bosons. We consider several scenarios with the SM ferm ions either living in the bulk or being localized at different points of an extra dimension. Global fits to electroweak observables provide lower boun ds on 1/R, which are generically in the 2-5 TeV range. We find, however, ce rtain models where the fit to electroweak observables is better than in the SM, because of an improvement in the prediction to the weak charge Q(W). W e also consider the case of softly-broken supersymmetric theories and we fi nd new non-decoupling effects that put new constraints on 1/R. If quarks of different families live in different points of the extra dimension, we fin d that the Kaluza-Klein modes of the SM gluons generate (at tree level) dan gerous flavor and CP-violating interactions. The lower bounds on 1/R can in crease in this case up to 5000 TeV, disfavoring these scenarios in the cont ext of TeV-strings.