Constraining UED mass spectra with electroweak precision tests and flavor physics

In models with universal extra dimensions (UED), all Standard Model fields are promoted to fields on the flat five dimensional spacetime, where the fifth dimension is compactified on S1/Z2. The masses of the Kaluza-Klein partners of the Standard model fields depend on the compactification radius R, but also on five-dimensional fermion masses (split-UED) and boundary localized operators (nUED), whose parameters are a priory not determined. In this talk, we present strongly improved bounds on the split-UED and the nUED model from electroweak precision tests as well as from flavor physics. We also show the implications of these bounds for the masses of the particles at the first Kaluza-Klein level, which dictate the LHC phenomenology of the UED model.