A Higgs conundrum with vector fermions

Abstract

Many models of beyond the standard model physics involve heavy colored fermions. We study models where the new fermions have vector interactions and examine the connection between electroweak precision measurements and Higgs production. In particular, for parameters that are allowed by precision measurements, we show that the gluon fusion Higgs cross section and the Higgs decay branching ratios must be close to those predicted by the standard model. The models we discuss thus represent scenarios with new physics that will be extremely difficult to distinguish from the minimal standard model. We pay particular attention to the decoupling properties of the vector fermions.