Making inflation work: Damping of density perturbations due to Planck energy cutoff
Abstract
In this paper we propose an alternative method for the computation of classical density perturbations from a quantum field in an inflationary scenario. We compute the power spectrum of density perturbations directly from vacuum fluctuations of the ``timetime'' component of the energymomentum tensor. We compute the inhomogeneous part of the correlation function <0T^{0}_{0}(x,t) T^{0}_{0}(y,t)0> for a massless minimally coupled scalar field in de Sitter space. The Fourier transform of this twopoint function leads to the scaleinvariant spectrum of perturbations, but is ultraviolet divergent. This expression can be made finite by introducing an (ad hoc) smalldistance cutoff in the proper length. We argue that this cutoff should be of the order of the Planck length, and show that, in such a case, the density fluctuations have the acceptable magnitude (~10^{4}) for the case of primordial inflation. Thus the inflationary scenario can be made to work without any finetuning.
 Publication:

Physical Review D
 Pub Date:
 April 1989
 DOI:
 10.1103/PhysRevD.39.2100
 Bibcode:
 1989PhRvD..39.2100P
 Keywords:

 98.80.Cq;
 98.60.Ac;
 98.80.Dr;
 Particletheory and fieldtheory models of the early Universe