Shih-Yuin Lin — Page 3

arXiv1997

Dynamically Broken Scale Invariance and Cosmology

A new scalar-tensor theory of gravity induced by dynamically broken scale invariance is proposed, and its cosmological implications are discussed. It is found that the model admits an inflation via the Hawking-Moss bubbling, but the inflation rate remains undetermined due to the strong gravity limit. In light of this, scale-invariant metric perturbations having a dominant tensor component can be generated without slow-rollover. In addition, the deviation from the standard hot big-bang is vanishingly small after inflation.

hep-ph↗

arXiv1997

Generalized Scale Invariant Gravity

We generalize the scale invariant gravity by allowing a negative kinetic energy term for the classical scalar field. This gives birth to a new scalar-tensor theory of gravity, in which the scalar field is in fact an auxiliary field. For a pure gravity theory without matter, the scale symmetric phase represents an equivalent class of gravity theories, which the Einstein gravity plus a cosmological constant belongs to under a special gauge choice. The one-loop quantum correction of the theory is calculated by using the Vilkovisky-DeWitt's method. We find that the scale symmetry is broken dynamically, and that the Einstein gravity is the ground state of the broken phase. We also briefly discuss the consequent cosmological implications. It is shown that the time-delay experiment restricts the present universe to be very close to the ground state.

hep-th↗