Speaker
Description
We explore the effective field theory of a vector field X_mu that has a Stückelberg mass. The absence of a gauge symmetry for X implies Lorentz-invariant operators are constructed directly from X_mu. Beyond the kinetic and mass terms, allowed interactions at the renormalizable level include X^4, H^2 X^2 and X^mu j_mu, where j_mu is a global current of the SM or of a hidden sector. We show that all of these interactions lead to scattering amplitudes that grow with powers of the energy E, except for the case of X_mu coupling to an exactly conserved current. Our analysis suggests there is no free lunch by appealing to Stückelberg for the mass of a vector field: the price paid for avoiding a dark Higgs sector is replaced by the non-generic set of interactions that the Stückelberg vector field must have to avoid amplitudes that grow with energy.
