000197580 001__ 197580
000197580 005__ 20190316235850.0
000197580 0247_ $$2doi$$a10.1103/PhysRevD.89.063505
000197580 022__ $$a0556-2821
000197580 037__ $$aARTICLE
000197580 245__ $$aKinetic initial conditions for inflation
000197580 260__ $$bAmerican Physical Society$$c2014
000197580 269__ $$a2014
000197580 336__ $$aJournal Articles
000197580 520__ $$aWe consider the classical evolution of the inflaton field and the Hubble parameter in homogeneous and isotropic single-field inflation models. Under an extremely broad assumption, we show that the Universe generically emerges from an initial singularity in a noninflating state where the kinetic energy of the inflaton dominates its potential energy. In this kinetically dominated regime, the dynamical equations admit simple analytic solutions are independent of the form the potential energy. In such models, these analytic solutions thus provide a simple way of setting the initial conditions from which to start the (usually numerical) integration of the coupled equations of motion. We illustrate this procedure by applying it to spatially flat models with polynomial and exponential potentials, and determine the background evolution in each case; generically the Hubble parameter and the inflation field as well as their time derivatives decrease during kinetic dominance until the onset of a brief period of fast-roll inflation prior to a slow-roll phase. We also calculate the approximate spectrum of scalar perturbations produced in each model and show that it exhibits a generic damping of power on large scales. This may be relevant to the apparent low-l falloff in the cosmic microwave background power spectrum.
000197580 700__ $$aHandley, Will
000197580 700__ $$0244433$$g137850$$aBréchet, Sylvain
000197580 700__ $$aLasenby, Anthony
000197580 700__ $$aHobson, Michael
000197580 773__ $$j89$$tPhysical Review -Series d-$$q063505
000197580 8564_ $$uhttps://infoscience.epfl.ch/record/197580/files/PhysRevD.89.pdf$$zn/a$$s1386413$$yn/a
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000197580 937__ $$aEPFL-ARTICLE-197580
000197580 973__ $$rREVIEWED$$sPUBLISHED$$aOTHER
000197580 980__ $$aARTICLE