Title: Constraints on dark photon models with generalized mixing            

Host: Prof. Csaba Csaki

Abstract: Additional U(1) gauge symmetries are one of the best motivated extensions of the Standard Model (SM), and they often include new gauge bosons with masses that can span several orders of magnitude. In this talk, we present a model in which the new abelian gauge boson, called dark photon (DP), can mix with the neutral gauge bosons of the SM through both kinetic and mass terms. Such more general mixing can be the result of an extended scalar sector. We further present a global fit to electroweak precision observables in our model, which is obtained by calculating the tree-level contributions due to the mixing with the DP, as well as the leading loop corrections to the oblique parameters due to the extended Higgs sector. We find that, in the gauge sector, the excluded region depends strongly on the vacuum expectation values (vevs) of the scalar fields. For moderate ratios of the vevs, the DP cannot be heavier than O(10 GeV).