Professor H. v. Lohneysen
Karlsruhe Institute of Technology (KIT)
We consider the evolution of linear cosmological perturbations during
inflation when a Weyl term is added to the action. The presence of the
ghost degrees of freedom implies that vector perturbations can no longer
be ignored and that scalar modes diverge in the newtonian gauge but remain
bounded in the comoving slicing.
We then show that these ghost degrees of freedom can be eliminated by a
simple mechanism that invokes spontaneous Lorentz symmetry breaking.
As a result the kinetic term of the tensor perturbations is corrected at
short wave lengths. This leads to a redefinition of the quantum vacuum
state, which could be imprinted on the amplitude of the spectrum of
primordial gravitational waves.