In this talk I explore possible implications of a direct coupling between the Higgs field and some hidden sector. After a general motivation for considering hidden sectors I devote the first part to discussing the case of a normal particle hidden sector and to show how electroweak symmetry breaking and the electroweak phase transition can be dramatically affected. In the second part I discuss the case of an unparticle hidden sector, showing explicitly how electroweak symmetry breaking triggers scale breaking and induces a mass gap for unparticles which has important effects on the phenomenological implications of (and bounds on) unparticles. Conversely I show how Higgs properties can be strongly influenced by unparticle admixture and how the Higgs can illuminate the structure of the unparticle sector.

Autonoma Madrid