Speaker: Pedro Schwaller, Argonne National Laboratory
Abstract: The discovery of the Higgs boson opens the possibility to probe new physics scenarios by analyzing Higgs production and decay rates. The loop induced decay to photon pairs is particularly sensitive to new physics contributions, and a possible enhanced rate for this decay has generated some interest in models that can explain it. I will present an extension of the SM with a family of vector-like leptons. Not only can this model explain an enhanced di-photon decay rate of the Higgs, but it also provides a dark matter candidate while being in agreement with electroweak precision constraints. The necessarily large Yukawa couplings affect the running of the Higgs self coupling, such that an ultra violet (UV) completion is needed below the 10 TeV scale. A promising solution is to embed the model into a supersymmetric grand unified theory. Using RGEs upper bounds on the lepton Yukawa couplings can be derived, which limits the possible enhancement of the di-photon rate. Additional enhancement can be obtained if also the new sleptons are light, and I explore the parameter regions that are compatible with GUT-scale vacuum stability, LEP limits and electroweak precision constraints.