  In the present paper, we discuss gravitational relaxation models for the
electroweak hierarchy problem. We show that modified gravity can naturally
relax the electroweak hierarchy problem where conformal transformation provides
a crucial rule about what modified gravity theories are favored to relax the
electroweak hierarchy. The conformal transformation connects different
gravitational theories and rescaling the metric changes the dimensional
parameters like the Higgs mass or the cosmological constant in different frames
drastically. When the electroweak scale is naturally realized by dynamical and
running behavior of dilatonic scalar field or scaling parameter, the modified
gravity theories can relax the electroweak hierarchy problem. We discuss the
theoretical and phenomenological validity of the gravitational relaxation
models.
