Bifurcated symmetry breaking in scalar-tensor gravity
  We present models that simultaneously predict presence of dark energy and
cold dark matter along with slow-roll inflation. The dark energy density is
found to be of order $({\rm a \;few \;meV})^4$, and the mass of dark matter
constituent is $\approx 1\,$ meV. These numbers are given in terms of the
present value of Hubble constant $H_0$ and the Plank energy $1/\sqrt{16 \pi
G_N}$: they are $(H_0 M_{\rm P})^2$ for the energy density and $(H_0 M_{\rm
P})^{1/2}$ for the dark matter constituent mass. The basic framework is a
multi-scalar tensor gravity with non-trivial conformal coupling to the Ricci
scalar curvature in the lagrangian density. The key for a right amount of dark
energy is to incorporate in a novel way the spatially homogeneous kinetic
contribution of Nambu-Goldstone modes in a spontaneously broken multi-scalar
field sector. Proposed theories are made consistent with general relativity
tests at small cosmological distances, yet are different from general
relativity at cosmological scales. Dark matter is generated as spatially
inhomogeneous component of the scalar system, with roughly comparable amount to
the dark energy. In some presented models a cosmological bifurcation of
symmetry breaking of scalar sector is triggered by the spontaneous breaking of
electroweak SU(2) $\times $ U(1) gauge symmetry, hence the separation occurring
simultaneously at the electroweak phase transition. The best experimental
method to test presented models is to search for the fifth-force type of scalar
exchange interaction with a force range, $O(10^{-2})$ cm, whose coupling to
matter is basically of gravitational strength.
